1. 15-1 CHAPTER 15 Gnathiferans and Smaller Lophotrochozoans

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3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-3 Protosomia Structure Blastocoel persists as a space or cavity between enteron and body wall Blastocoel persists as a space or cavity between enteron and body wall Lacks the peritoneal lining of a true coelom Lacks the peritoneal lining of a true coelom Pseudocoel Pseudocoel Some describe body plan as blastocoelomate Some describe body plan as blastocoelomate Pseudocoelom may be filled with fluid or gelatinous material with mesenchyme cells Pseudocoelom may be filled with fluid or gelatinous material with mesenchyme cells Provides space for development of digestive, excretory, and reproductive systems Provides space for development of digestive, excretory, and reproductive systems

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5. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-5 Simpler to distribute materials throughout the body Simpler to distribute materials throughout the body Provides storage area for waste products Provides storage area for waste products Acts as a hydrostatic skeleton Acts as a hydrostatic skeleton Permit internal circulation Permit internal circulation Protosomia

6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-6 Phylogeny Large clade sometimes called a superphylum Large clade sometimes called a superphylum Protostome phyla are divided between two large clades Protostome phyla are divided between two large clades Lophotrochozoa and Ecdysozoa Lophotrochozoa and Ecdysozoa Lophotrochozoa (10 Phyla) Lophotrochozoa (10 Phyla) Ancestors possessed complex cuticular jaws Ancestors possessed complex cuticular jaws Gnathostomata Gnathostomata Micrognathozoa Micrognathozoa Rotifera Rotifera Acanthoephala Acanthoephala Protosomia

7. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-7 6 other lophotrochozoan phyla 6 other lophotrochozoan phyla Gastrotricha Gastrotricha Tiny aquatic animals that may be closely related to gnathiferans Tiny aquatic animals that may be closely related to gnathiferans Molecular characteristics place the following with Lophotrochozoa Molecular characteristics place the following with Lophotrochozoa Cycliophora Cycliophora Entoprocta Entoprocta Ectoprocta Ectoprocta Brachiopoda Brachiopoda Phoronida Phoronida Protosomia

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9. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-9 Clade Gnathifera Possess small cuticular jaws with a homologous microstructure Possess small cuticular jaws with a homologous microstructure Numbers of pairs of jaws vary Numbers of pairs of jaws vary Gnathostomulida, Micrognathozoa, and Rotifera Gnathostomulida, Micrognathozoa, and Rotifera Tiny, free-living, aquatic animals Tiny, free-living, aquatic animals Acanthocephalans Acanthocephalans Worm-like endoparasites living as adults in fish or other vertebrates Worm-like endoparasites living as adults in fish or other vertebrates Protosomia

10. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-10 Rotifera and Acanthocephala Rotifera and Acanthocephala Presumed sister taxa Presumed sister taxa Form a clade called Syndermata Form a clade called Syndermata Have eutelic syncytial epidermis Have eutelic syncytial epidermis Grouping is controversial Grouping is controversial Protosomia

11. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-11 Phylum Gnathostomulida Characteristics Delicate worm-like animals, less than 2 mm long Delicate worm-like animals, less than 2 mm long Over 80 species of jawed worms in 18 genera have been described Over 80 species of jawed worms in 18 genera have been described Live in crevices of sediment and silt and endure low oxygen Live in crevices of sediment and silt and endure low oxygen Epidermis is ciliated Epidermis is ciliated One cilium per cell One cilium per cell Glide, swim, and bend head side to side Glide, swim, and bend head side to side

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13. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-13 Feed by scraping bacteria and fungi from the substratum with a pair of jaws on the pharynx Feed by scraping bacteria and fungi from the substratum with a pair of jaws on the pharynx Acoelomate with a poorly developed parenchyma layer Acoelomate with a poorly developed parenchyma layer Sexual stages include males, females, and hermaphrodites Sexual stages include males, females, and hermaphrodites Fertilization is internal Fertilization is internal Phylum Gnathostomulida

14. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-14 Phylum Micrognathozoa Characteristics Tiny animals that live interstitially (between sand grains) Tiny animals that live interstitially (between sand grains) Body consists of a two-part head, a thorax, and abdomen with short tail Body consists of a two-part head, a thorax, and abdomen with short tail Cellular epidermis has dorsal plates Cellular epidermis has dorsal plates Move using cilia and have a unique ventral ciliary adhesive pad that produces glue Move using cilia and have a unique ventral ciliary adhesive pad that produces glue Three pairs of complex jaws Three pairs of complex jaws

15. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-15 Simple gut Simple gut Anus opens to outside only periodically Anus opens to outside only periodically Reproductive system is not well understood Reproductive system is not well understood Only female reproductive organs have been identified Only female reproductive organs have been identified May reproduce parthenogenetically May reproduce parthenogenetically Cleavage and subsequent development have not been studied Cleavage and subsequent development have not been studied Phylum Micrognathozoa

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17. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-17 Phylum Rotifera Characteristics Possess a ciliated crown, the corona, that beats like a rotating wheel Possess a ciliated crown, the corona, that beats like a rotating wheel Approximately 2000 species Approximately 2000 species Aquatic species are mostly benthic but some are pelagic Aquatic species are mostly benthic but some are pelagic Highly diverse in color, size and shape Highly diverse in color, size and shape Some are colonial Some are colonial Floaters are globular, creepers are elongated, and sessile forms are vase-like Floaters are globular, creepers are elongated, and sessile forms are vase-like Many endure desiccation and temperature changes by encystment Many endure desiccation and temperature changes by encystment

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20. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-20 Form and Function Rotifer body has a head, trunk and tail Rotifer body has a head, trunk and tail Only corona is ciliated Only corona is ciliated Ciliated corona surrounds a nonciliated central area with sensory bristles and mouth Ciliated corona surrounds a nonciliated central area with sensory bristles and mouth Corona is often a pair of trochal discs Corona is often a pair of trochal discs Beating of the cilia help in feeding and locomotion Beating of the cilia help in feeding and locomotion Some have a secreted cuticle Some have a secreted cuticle Phylum Rotifera

21. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-21 All have a fibrous epidermal layer, and a lorica that may be case-like All have a fibrous epidermal layer, and a lorica that may be case-like Narrow foot has one to four toes and may be retractile Narrow foot has one to four toes and may be retractile Attaches with pedal glands that secrete an adhesive Attaches with pedal glands that secrete an adhesive Phylum Rotifera

22. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-22 Internal Features Under the cuticle, a syncytial epidermis secretes cuticle and bands of subepidermal muscles Under the cuticle, a syncytial epidermis secretes cuticle and bands of subepidermal muscles Pseudocoel is large, filled with fluid, and a network of mesenchymal ameboid cells Pseudocoel is large, filled with fluid, and a network of mesenchymal ameboid cells Digestion Digestion Coronal cilia sort out larger unsuitable particles Coronal cilia sort out larger unsuitable particles Mastax is a muscular pharynx equipped with hard jaws, the trophi Mastax is a muscular pharynx equipped with hard jaws, the trophi Trappers have a funnel-shaped area around the mouth Trappers have a funnel-shaped area around the mouth Side lobes fold inward to entrap prey Side lobes fold inward to entrap prey Phylum Rotifera

23. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-23 Hunters project trophi to seize prey Hunters project trophi to seize prey Salivary and gastric glands secrete enzymes for extracellular digestion Salivary and gastric glands secrete enzymes for extracellular digestion The stomach absorbs nutrients The stomach absorbs nutrients Osmoregulation Osmoregulation Pair of protonephridial tubules with flame cells empty into a common bladder Pair of protonephridial tubules with flame cells empty into a common bladder Bladder pulsates and empties into cloaca Bladder pulsates and empties into cloaca Water enters by the mouth Water enters by the mouth Bilobed brain is dorsal to the mastax with paired nerves leading to the organs Bilobed brain is dorsal to the mastax with paired nerves leading to the organs Sensory organs include eyespots, sensory bristles and papillae, and ciliated pits and dorsal antennae Sensory organs include eyespots, sensory bristles and papillae, and ciliated pits and dorsal antennae Phylum Rotifera

24. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-24 Classification Class Seisonidea Class Seisonidea Class Bdelloidea Class Bdelloidea Class Monogononta Class Monogononta Phylum Rotifera

25. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-25 Reproduction Dioecious Dioecious Males smaller than females Males smaller than females In some classes, males are unknown, and in others, males occur only briefly In some classes, males are unknown, and in others, males occur only briefly Female systems may provide yolk to developing ova by cytoplasmic bridges Female systems may provide yolk to developing ova by cytoplasmic bridges Ovaries and yolk glands may be combined as germovitallaria Ovaries and yolk glands may be combined as germovitallaria Phylum Rotifera

26. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-26 Bdelloidea females are parthenogenetic, producing diploid eggs that hatch into diploid females Bdelloidea females are parthenogenetic, producing diploid eggs that hatch into diploid females Monogononta females produce Monogononta females produce Diploid amictic eggs that form diploid females Diploid amictic eggs that form diploid females by parthenogenesis or Haploid mictic eggs that, if not fertilized, become haploid males Haploid mictic eggs that, if not fertilized, become haploid males Males have single testis and ciliated sperm duct running to a genital pore and copulatory organ Males have single testis and ciliated sperm duct running to a genital pore and copulatory organ Phylum Rotifera

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28. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-28 Mating is by hypodermic penetration Mating is by hypodermic penetration Sperm injected into the pseudocoel of the female Sperm injected into the pseudocoel of the female Females hatch with adult features and mature in a few days Females hatch with adult features and mature in a few days Males are mature at hatching Males are mature at hatching Phylum Rotifera

29. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-29 Phylogeny of Rotifera Recent molecular work questions the taxonomic affinity of some groups and distributions may be an artifact of morphological characteristics rather than taxonomic similarities Recent molecular work questions the taxonomic affinity of some groups and distributions may be an artifact of morphological characteristics rather than taxonomic similarities According to traditional classification, Rotifera has three classes According to traditional classification, Rotifera has three classes Some authorities would rather put Seisonidea and Bdelloidea into orders within a class called Digonata Some authorities would rather put Seisonidea and Bdelloidea into orders within a class called Digonata Phylum Rotifera

30. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-30 Others divide the phylum into two classes: one containing the seisonids and the other containing the bdelloids and monogononts under the name Eurotatoria Others divide the phylum into two classes: one containing the seisonids and the other containing the bdelloids and monogononts under the name Eurotatoria At present, Acanthocephala is the sister taxon to Rotifera At present, Acanthocephala is the sister taxon to Rotifera Phylum Rotifera

31. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-31 Phylum Acanthocephala Diversity All spiny-headed worms are parasites in the intestines of vertebrates All spiny-headed worms are parasites in the intestines of vertebrates Over 1100 species known Over 1100 species known Occur worldwide and parasitize fish, birds, and mammals Occur worldwide and parasitize fish, birds, and mammals Proboscis has rows of recurved spines that penetrate and may rupture host intestines Proboscis has rows of recurved spines that penetrate and may rupture host intestines Larvae develop in crustaceans or insects Larvae develop in crustaceans or insects

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33. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-33 Form and Function Body somewhat flattened Body somewhat flattened Body wall is syncytial and surface has minute crypts to increase surface area Body wall is syncytial and surface has minute crypts to increase surface area About 80% of tegument is a lacunar system of fluid-filled canals that may distribute nutrients and remove wastes from muscles About 80% of tegument is a lacunar system of fluid-filled canals that may distribute nutrients and remove wastes from muscles No heart No heart Function provided by lacunar fluid Function provided by lacunar fluid Both longitudinal and circular body wall muscles are present Both longitudinal and circular body wall muscles are present Proboscis with hooks can be inverted into a proboscis receptacle by retractor muscles Proboscis with hooks can be inverted into a proboscis receptacle by retractor muscles Phylum Acanthocephala

34. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-34 Two lemnisci may serve as fluid reservoirs when the proboscis is retracted Two lemnisci may serve as fluid reservoirs when the proboscis is retracted No respiratory system No respiratory system Protonephridia with flame cells, if present, perform excretory functions Protonephridia with flame cells, if present, perform excretory functions Lack a digestive tract Lack a digestive tract Absorbs nutrients across tegument, which bears some enzymes Absorbs nutrients across tegument, which bears some enzymes Constantly phosphorylates glucose so a gradient remains to constantly absorb more Constantly phosphorylates glucose so a gradient remains to constantly absorb more Males have a pair of testes Males have a pair of testes During copulation, sperm are ejected into the vagina and travel into the pseudocoel During copulation, sperm are ejected into the vagina and travel into the pseudocoel Phylum Acanthocephala

35. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-35 Female ovarian tissue breaks up into ovarian balls that rupture and float free in pseudocoel Female ovarian tissue breaks up into ovarian balls that rupture and float free in pseudocoel Uterine bell receives developing shelled embryos and passes them to uterus Uterine bell receives developing shelled embryos and passes them to uterus Shelled embryos discharged in the feces Shelled embryos discharged in the feces Hatch when eaten by an intermediate host, often grubs Hatch when eaten by an intermediate host, often grubs No species normally parasitizes humans No species normally parasitizes humans Phylum Acanthocephala

36. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-36 Acanthocephalans penetrate the intestinal wall with spiny proboscis Acanthocephalans penetrate the intestinal wall with spiny proboscis Remarkably little inflammation on host wall, but pain of infection is intense Remarkably little inflammation on host wall, but pain of infection is intense Larval acanthors burrow through beetle intestine Larval acanthors burrow through beetle intestine Develop into juvenile cystacanths in the insect hemocoel Develop into juvenile cystacanths in the insect hemocoel Phylum Acanthocephala

37. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-37 Phylum Gastrotricha Small, ventrally flattened animals Small, ventrally flattened animals Usually less than 1 mm in length Usually less than 1 mm in length Live in fresh, brackish, and salt water Live in fresh, brackish, and salt water Usually elongated with a convex dorsal surface bearing a pattern of bristles, spines, or scales, and a flattened ciliated ventral surface Usually elongated with a convex dorsal surface bearing a pattern of bristles, spines, or scales, and a flattened ciliated ventral surface Cells on ventral surface may be monociliated or multiciliated Cells on ventral surface may be monociliated or multiciliated Head is often lobed and ciliated Head is often lobed and ciliated Tail may be greatly elongated or forked in some species Tail may be greatly elongated or forked in some species No body cavity No body cavity

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40. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-40 Phylogeny of Acanthocephala Divided traditionally into three classes: Archiacanthocephala, Eocanthocephala, and Palaeacanthocephala Divided traditionally into three classes: Archiacanthocephala, Eocanthocephala, and Palaeacanthocephala Recent molecular work has suggested that the phylum status of the Acanthocephala is unwarranted, and that they may be a class of highly derived rotifers Recent molecular work has suggested that the phylum status of the Acanthocephala is unwarranted, and that they may be a class of highly derived rotifers There is still debate as to which rotifer class contains animals most closely related to the acanthocephalans There is still debate as to which rotifer class contains animals most closely related to the acanthocephalans Phylum Acanthocephala

41. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-41 Phylum Cycliophora Characteristics Live exclusively on mouthparts of marine decapod crustaceans in northern hemisphere Live exclusively on mouthparts of marine decapod crustaceans in northern hemisphere Attach to bristles with an adhesive disc on the end of an acellular stalk Attach to bristles with an adhesive disc on the end of an acellular stalk Feed by collecting bacteria or bits of food dropped from their lobster host on a ring of compound cilia that surrounds the mouth Feed by collecting bacteria or bits of food dropped from their lobster host on a ring of compound cilia that surrounds the mouth Simple body plan Simple body plan Mouth leads to U-shaped gut ending with an anus that opens outside the ciliated ring Mouth leads to U-shaped gut ending with an anus that opens outside the ciliated ring Acoelomate Acoelomate Cellular epidermis surrounded by a cuticle Cellular epidermis surrounded by a cuticle

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43. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-43 Life cycle has sexual and asexual phases Life cycle has sexual and asexual phases Feeding animals form internal buds called Pandora larvae Feeding animals form internal buds called Pandora larvae Become new feeding individuals upon release Become new feeding individuals upon release Cloned members occupy vacant areas on the lobster mouthparts Cloned members occupy vacant areas on the lobster mouthparts In sexual reproduction In sexual reproduction Male larvae is released and settles atop another animal housing a female larvae Male larvae is released and settles atop another animal housing a female larvae Male larvae produce secondary males with reproductive organs Male larvae produce secondary males with reproductive organs Internal fertilization occurs as secondary male mates with a female larva leaving the body of a feeding animal Internal fertilization occurs as secondary male mates with a female larva leaving the body of a feeding animal Phylum Cycliophora

44. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-44 Once fertilization occurs Once fertilization occurs Chordoid larva develops inside the body of its mother, consuming it Chordoid larva develops inside the body of its mother, consuming it Relationships to other phyla are controversial Relationships to other phyla are controversial The discoverers, P. Funch and R.M. Kristensen, consider the organisms to be protostomes and most analyses place them in Lophotrochozoa The discoverers, P. Funch and R.M. Kristensen, consider the organisms to be protostomes and most analyses place them in Lophotrochozoa Phylum Cycliophora

45. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-45 Phylum Entoprocta Diversity About 150 species occur worldwide About 150 species occur worldwide Usually in marine environments Usually in marine environments Less than 5 mm long and mostly microscopic, resembling hydroid cnidarians Less than 5 mm long and mostly microscopic, resembling hydroid cnidarians Urnatella gracilis Urnatella gracilis Common freshwater species in North America Common freshwater species in North America

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47. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-47 Form and Function Body or calyx is cup shaped and bears a circular crown of ciliated tentacles Body or calyx is cup shaped and bears a circular crown of ciliated tentacles Attaches by a stalk with adhesive glands Attaches by a stalk with adhesive glands Tentacles (3-30) and stalk are continuations of the body wall Tentacles (3-30) and stalk are continuations of the body wall Body wall has a cuticle, cellular epidermis and longitudinal muscles Body wall has a cuticle, cellular epidermis and longitudinal muscles Tentacles on lateral and inner surfaces Tentacles on lateral and inner surfaces Can roll inward but cannot be retracted into the calyx Can roll inward but cannot be retracted into the calyx Gut is U-shaped with both mouth and anus opening within the circle of tentacles Gut is U-shaped with both mouth and anus opening within the circle of tentacles Phylum Entoprocta

48. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-48 Long cilia on sides generate current bringing in particles Long cilia on sides generate current bringing in particles Short cilia on inner surfaces capture food and direct it to mouth Short cilia on inner surfaces capture food and direct it to mouth Pair of protonephridia embedded in gelatinous parenchyma Pair of protonephridia embedded in gelatinous parenchyma Well-developed nerve ganglion on the ventral side of stomach Well-developed nerve ganglion on the ventral side of stomach No circulatory or respiratory organs No circulatory or respiratory organs Some are monoecious, some dioecious, and some first produce sperm and later eggs Some are monoecious, some dioecious, and some first produce sperm and later eggs Phylum Entoprocta

49. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-49 Fertilized eggs develop in a brood pouch between gonopore and anus Fertilized eggs develop in a brood pouch between gonopore and anus Modified spiral cleavage leads to trochophore-like larva Modified spiral cleavage leads to trochophore-like larva Phylum Entoprocta

50. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-50 Lophophorates Phylogeny Phylogeny Phylum Ectoprocta Phylum Ectoprocta Phylum Brachiopoda Phylum Brachiopoda Phylum Phoronida Phylum Phoronida Belong within the lophotrochozoan subgroup of protostomes Belong within the lophotrochozoan subgroup of protostomes Grouping very controversial Grouping very controversial Evidence comes from sequence analysis of genes encoding small-subunit ribosomal RNA Evidence comes from sequence analysis of genes encoding small-subunit ribosomal RNA Some aspects of development place these taxa within Deuterostomia Some aspects of development place these taxa within Deuterostomia Phylum Entoprocta

51. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-51 Characteristics Characteristics Members of these 3 taxa possess a feeding device called a lophophore Members of these 3 taxa possess a feeding device called a lophophore Unique arrangement of ciliated tentacles borne on a ridge or fold on the body wall Unique arrangement of ciliated tentacles borne on a ridge or fold on the body wall Tentacles are hollow and contain an extension of the mesocoel Tentacles are hollow and contain an extension of the mesocoel Ciliated tentacles are also a respiratory device permitting gas exchange between surrounding water and internal coelomic fluid Ciliated tentacles are also a respiratory device permitting gas exchange between surrounding water and internal coelomic fluid Gut is U-shaped Gut is U-shaped Mouth opens inside the lophophore ring, and the anus opens outside the ring Mouth opens inside the lophophore ring, and the anus opens outside the ring Phylum Entoprocta

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53. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-53 Epistome, a flap of tissue, contains an extension of the protocoel Epistome, a flap of tissue, contains an extension of the protocoel Region housing the mesocoel is the mesosome Region housing the mesocoel is the mesosome Region housing the metacoel is called metasome Region housing the metacoel is called metasome In Ectoprocta In Ectoprocta Fluid-filled mesocoel and metacoel cavities are part of the hydraulic system for lophophore extension Fluid-filled mesocoel and metacoel cavities are part of the hydraulic system for lophophore extension Much remains to be discovered about these animals Much remains to be discovered about these animals Phylum Entoprocta

54. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-54 Ectoprocts Characteristics Characteristics Contains aquatic animals that often encrust hard surfaces Contains aquatic animals that often encrust hard surfaces Most are sessile, some slide slowly, and others crawl actively across surfaces Most are sessile, some slide slowly, and others crawl actively across surfaces Mostly colony builders Mostly colony builders Each member less than 0.5 mm in length Each member less than 0.5 mm in length Colony members are called zooids Colony members are called zooids Zooids feed by extending lophophores into surrounding water to collect tiny particles Zooids feed by extending lophophores into surrounding water to collect tiny particles Zooids secrete exoskeleton in which they live in Zooids secrete exoskeleton in which they live in Phylum Entoprocta

55. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-55 Exoskeleton (zoecium) may be gelatinous, chitinous, or stiffened with calcium and possibly impregnated with sand Exoskeleton (zoecium) may be gelatinous, chitinous, or stiffened with calcium and possibly impregnated with sand Shape may be boxlike, vaselike, oval, or tubular Shape may be boxlike, vaselike, oval, or tubular Approximately 4500 living species Approximately 4500 living species Inhabit both shallow freshwater and marine habitats Inhabit both shallow freshwater and marine habitats Some colonies form limy encrustations on seaweed, shells, and rocks Some colonies form limy encrustations on seaweed, shells, and rocks Others form fuzzy or shrubby growths or erect branching colonies Others form fuzzy or shrubby growths or erect branching colonies Freshwater colonies may form mosslike colonies on stems of plants or on rocks Freshwater colonies may form mosslike colonies on stems of plants or on rocks Phylum Entoprocta

56. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-56 Form and Function Form and Function Each member lives in a tiny chamber called the zoecium Each member lives in a tiny chamber called the zoecium Zooids consists of a feeding polypide and a case- forming cystid Zooids consists of a feeding polypide and a case- forming cystid Polypide includes the lophophore, digestive tract, muscles, and nerve centers Polypide includes the lophophore, digestive tract, muscles, and nerve centers Cystid includes the body wall of an animal, together with its secreted exoskeleton Cystid includes the body wall of an animal, together with its secreted exoskeleton Polypides pop up to feed, but withdraw quickly at the slightest disturbance Polypides pop up to feed, but withdraw quickly at the slightest disturbance To extend tentacular crown, muscles contract To extend tentacular crown, muscles contract Increases hydrostatic pressure within the body cavity and forces out lophophore Increases hydrostatic pressure within the body cavity and forces out lophophore Other muscles contract to withdraw crown to safety Other muscles contract to withdraw crown to safety Phylum Entoprocta

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58. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-58 To feed, the lophophore is extended and tentacles spread out into a funnel To feed, the lophophore is extended and tentacles spread out into a funnel Cilia on tentacles draw water into funnel Cilia on tentacles draw water into funnel Food particles caught by cilia in the funnel are drawn into the mouth by the pumping action of the muscular pharynx and by the action of the cilia Food particles caught by cilia in the funnel are drawn into the mouth by the pumping action of the muscular pharynx and by the action of the cilia Digestion begins extracellularly in the stomach and is completed intracellularly within the intestine Digestion begins extracellularly in the stomach and is completed intracellularly within the intestine Respiratory, vascular, and excretory organs absent Respiratory, vascular, and excretory organs absent Gas exchange is through body surface Gas exchange is through body surface Ganglionic mass and a nerve ring around the pharynx Ganglionic mass and a nerve ring around the pharynx No sense organs No sense organs Phylum Entoprocta

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60. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-60 Reproduction Reproduction Most hermaphroditic Most hermaphroditic Some species shed eggs into seawater, but most brood their eggs Some species shed eggs into seawater, but most brood their eggs Brooding occurs within coelom and some have an external chamber called an ovicell Brooding occurs within coelom and some have an external chamber called an ovicell Sometimes embryos proliferate asexually from the initial embryo in a process called polyembryony Sometimes embryos proliferate asexually from the initial embryo in a process called polyembryony Cleavage is radial but mosaic Cleavage is radial but mosaic Larva of nonbrooding species have a functional gut and swim for a few months before settling Larva of nonbrooding species have a functional gut and swim for a few months before settling Phylum Entoprocta

61. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-61 Larva of brooding species do not feed and settle after a brief free-swimming existence Larva of brooding species do not feed and settle after a brief free-swimming existence Attach to substratum by secretions from an adhesive sac, then metamorphose to adult form Attach to substratum by secretions from an adhesive sac, then metamorphose to adult form New colonies begin from this single metamorphosed primary zooid, called an ancestrula New colonies begin from this single metamorphosed primary zooid, called an ancestrula Ancestrula undergoes asexual budding to produce many zooids of a colony Ancestrula undergoes asexual budding to produce many zooids of a colony Freshwater ectoprocts undergo budding that produces statoblasts Freshwater ectoprocts undergo budding that produces statoblasts Hard, resistant capsules containing a mass of germinative cells Hard, resistant capsules containing a mass of germinative cells Phylum Entoprocta

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63. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-63 Phylum Brachiopoda Characteristics Also called lamp shells Also called lamp shells Ancient group Ancient group Approximately 325 living species Approximately 325 living species Fossil record indicates 12,000 species lived during Paleozoic and Mesozoic seas Fossil record indicates 12,000 species lived during Paleozoic and Mesozoic seas Attached, bottom-dwelling, marine forms that inhabit mostly shallow water Attached, bottom-dwelling, marine forms that inhabit mostly shallow water Externally resemble bivalved mollusks Externally resemble bivalved mollusks Attach to substrate directly or by fleshy stalk, the pedicel Attach to substrate directly or by fleshy stalk, the pedicel

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65. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-65 Shell valves distinguish the two classes of brachiopods Shell valves distinguish the two classes of brachiopods Articulata Articulata Connecting hinge with an interlocking tooth- and-socket arrangement Connecting hinge with an interlocking tooth- and-socket arrangement Inarticulata Inarticulata Held together by muscles Held together by muscles Body occupies only the posterior space between valves Body occupies only the posterior space between valves Extensions of the body wall form mantle lobes Extensions of the body wall form mantle lobes Line and secrete the shell Line and secrete the shell Phylum Brachiopoda

66. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-66 Have large horseshoe-shaped lophophore in the anterior mantle Have large horseshoe-shaped lophophore in the anterior mantle Ciliated tentacles are involved in feeding and respiration Ciliated tentacles are involved in feeding and respiration Food sources include organic detritus and some algae Food sources include organic detritus and some algae Most have separate sexes Most have separate sexes Fertilization is external Fertilization is external Cleavage is radial Cleavage is radial Coelom and mesoderm formation in some is enterocoelic Coelom and mesoderm formation in some is enterocoelic Phylum Brachiopoda

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68. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-68 Phylum Phoronida Characteristics Contains ~20 species of small, wormlike animals Contains ~20 species of small, wormlike animals Most live on the substrate of shallow coastal waters, especially in temperate seas Most live on the substrate of shallow coastal waters, especially in temperate seas Range in length from few mm to 30 cm Range in length from few mm to 30 cm Each worm secretes a leathery or chitinous tube in which it lies free, but never leaves Each worm secretes a leathery or chitinous tube in which it lies free, but never leaves Tubes may be anchored singly or in a tangled mass on rocks, shells, or pilings or buried in sand Tubes may be anchored singly or in a tangled mass on rocks, shells, or pilings or buried in sand

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70. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-70 Thrust out tentacles on lophophore for feeding but withdraw into the tube when disturbed Thrust out tentacles on lophophore for feeding but withdraw into the tube when disturbed Lophophore has two parallel ridges curved in a horseshoe shape Lophophore has two parallel ridges curved in a horseshoe shape Cilia in tentacles direct water currents toward groove between two ridges on lophophore Cilia in tentacles direct water currents toward groove between two ridges on lophophore Plankton and detritus caught in current become entangled in mucus and are carried by cilia to mouth Plankton and detritus caught in current become entangled in mucus and are carried by cilia to mouth Anus lies dorsal to mouth Anus lies dorsal to mouth Phylum Phoronida

71. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-71 Cilia in stomach of the U-shaped gut aid in food movement Cilia in stomach of the U-shaped gut aid in food movement Body wall consists of cuticle, epidermis, and both longitudinal and circular muscles Body wall consists of cuticle, epidermis, and both longitudinal and circular muscles Protocoel is present as small cavity in epistome Protocoel is present as small cavity in epistome Septum separates mesocoel and metacoel Septum separates mesocoel and metacoel Phylum Phoronida

72. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-72 Extensive system of contractile blood vessels in functionally closed circulatory system Extensive system of contractile blood vessels in functionally closed circulatory system No heart No heart Blood contains hemoglobin within nucleated cells Blood contains hemoglobin within nucleated cells Pair of metanephridia Pair of metanephridia Nerve ring sends nerves to tentacles and body wall Nerve ring sends nerves to tentacles and body wall System is diffuse and lacks distinct ganglion System is diffuse and lacks distinct ganglion Phylum Phoronida

73. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-73 Monoecious and dioecious Monoecious and dioecious One species reproduces asexually One species reproduces asexually Fertilization may be internal or external Fertilization may be internal or external Cleavage is radial Cleavage is radial Phylum Phoronida

74. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-74 Phylogeny Analysis of rRNA gene sequencing suggests that after the ancestral deuterostome diverged from ancestral protostomes Analysis of rRNA gene sequencing suggests that after the ancestral deuterostome diverged from ancestral protostomes Protostomes split into two large groups Protostomes split into two large groups Ecdysozoa that molt Ecdysozoa that molt Lophotrochozoa that exhibit lophophore feeding and trochophore-like larvae Lophotrochozoa that exhibit lophophore feeding and trochophore-like larvae Most lophotrochozoans share some developmental features Most lophotrochozoans share some developmental features Spiral mosaic cleavage and formation of mouth from embryonic blastopore Spiral mosaic cleavage and formation of mouth from embryonic blastopore No common body plan No common body plan

75. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-75 Lophotrochozoan protostomes are a heterogeneous group for which evolutionary branching order remains to be determined Lophotrochozoan protostomes are a heterogeneous group for which evolutionary branching order remains to be determined DNA sequence analysis has led to the conclusion that acanthocephalans are highly derived rotifers DNA sequence analysis has led to the conclusion that acanthocephalans are highly derived rotifers Sequences put Acanthocephala and Rotifera together as clade Syndermata, sharing a eutelic syncytial epidermis Sequences put Acanthocephala and Rotifera together as clade Syndermata, sharing a eutelic syncytial epidermis Syndermata is placed with Micrognathozoa and Gnathostomulida in clade Gnathifera Syndermata is placed with Micrognathozoa and Gnathostomulida in clade Gnathifera Controversial placement of Cycliophora, Gastrotricha, and Platyhelminthes close to Gnathifera Controversial placement of Cycliophora, Gastrotricha, and Platyhelminthes close to Gnathifera Phylogeny

76. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-76 Entoprocts and ectoprocts Entoprocts and ectoprocts Once considered both Bryozoa, but ectoprocts have been broken out as true coelomate animals Once considered both Bryozoa, but ectoprocts have been broken out as true coelomate animals Sequence analysis now places them both in the lophotrochozoan phyla Sequence analysis now places them both in the lophotrochozoan phyla Ectoprocts, brachiopods, and phoronids Ectoprocts, brachiopods, and phoronids Share a lophophore and a tripartite coelom Share a lophophore and a tripartite coelom Other features are mixtures of developmental traits from both protostomes and deuterostomes Other features are mixtures of developmental traits from both protostomes and deuterostomes Debate continues on whether the lophophorates form a clade or whether the group members, either individually or collectively belong within Protostomia or Deuterostomia Debate continues on whether the lophophorates form a clade or whether the group members, either individually or collectively belong within Protostomia or Deuterostomia Phylogeny