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INVERTEBRATES About 97 percent of all animals are invertebrates.

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1 INVERTEBRATES About 97 percent of all animals are invertebrates.

2 Introduction to Animals

3 Over a million different types have been identified! Animals likely evolved from protozoans. Kingdom Protista

4 Section 1 1.blastula (596) 2.ectoderm (596) 3.endoderm (596) 4.mesoderm (596) 5.body plan (598) 6.asymmetrical (598) 7.radial symmetry (598) 8.bilateral symmetry (598) 9.cephalization (599) 10.coelom (600) 11.acoelomate (600) 12.pseudocoelomate (600) 13.coelomate (600) 14.phylogenetic tree (602)

5 Characteristics of Animals All animals share these general features: 1.heterotrophy, 2.mobility, 3.multicellularity, 4.sexual reproduction, 5.diploidy, 6.the absence of a cell wall, 7.cells organized as tissues, and 8.blastula formation.

6 heterotrophy, Cant make their own food… must eat things.

7 mobility, Animals can swim, crawl, walk, run, and even fly. Some only move in the larval stage… the sponge

8 multicellularity, Made up of more then one cell! Although animals come in a wide range of sizes, the cell sizes are all very similar!

9 sexual reproduction Almost all animals reproduce sexually by producing gametes. Unlike the egg cells, the sperm cells of animals have a flagella and are highly mobile.

10 diploidy, adults have two copies of each chromosome, one inherited from their father and one from their mother.

11 the absence of a cell wall, Among the cells of multicellular organisms, only animal cells lack rigid cell walls. The absence of a cell wall has allowed animals mobility that other multicellular organisms do not have.

12 blastula formation In all animals except sponges, the zygote (fertilized egg cell) undergoes cell divisions that form a hollow ball of cells called a blastula.

13 cells organized as tissues Cells within the blastula eventually develop into three distinct layers of cells endoderm, ectoderm, and mesoderm. These layers are called the primary tissue layers because they give rise to all of the tissues and organs of the adult body.

14 tissues tissues are groups of cells with a common structure that work together to perform a specific function.

15 Body Symmetry All animals have their own particular body plan, a term used to describe an animals shape, symmetry, and internal organization.

16 3 body symmetry

17 radial symmetry Animals with radial symmetry have body parts arranged around a central axis.

18 bilateral symmetry Animals with bilateral symmetry have a distinct right and left half, and most display cephalization.

19 body plans Animals have one of three basic body plans: acoelomate, pseudocoelomate, and coelomate.

20 coelom a body cavity, coelom or (SEE luhm), a fluid-filled space found between the body wall and the digestive tract (gut). This space is lined with cells that come from mesoderm.

21 Coelomates are either protostomes or deuterostomes.protostomesdeuterostomes Protostomes (first mouth) are coelomates whose embryonic development shows a blastopore associated with a mouth. Deuterostomes (second mouth) are coelomates whose embryonic development shows a blastopore associated with an anus, with a second opening forming the mouth (hence "second mouth").

22 acoelomate Animals with no body cavity are called acoelomate (ay SEEL oh mayts). The space between an acoelomates body wall and gut is completely filled with tissues

23 pseudocoelomate have a body cavity located between the mesoderm and endoderm. Their body cavity is called a pseudocoelom (false coelom)

24 Body plans

25 Segmentation Segmentation in body structure underlies the organization of all advanced animals.


27 Some animals have their bodies divided into segments. This allows them to specialize certain segments, such as for antennae, eyes, claws, etc. Humans, insects, and earthworms are examples of segmented animals.

28 animal phyla There are about 35 animal phyla, which contain an extraordinary range of body forms and body systems..

29 phylogenetic tree To visually represent the relationships among various groups of animals, scientists often use a type of branching diagram called a phylogenetic tree. It shows how animals are related through evolution

30 Scientists classify animals using several different types of data, which include comparing anatomy and physiology, patterns of development, and DNA.

31 The animal kingdom is divided in two groups: vertebrates and invertebrates


33 Animals are characteristically multicellular heterotrophs whose cells lack cell wallsmulticellular heterotrophscell walls Animals likely evolved from protozoans. Kingdom Protista

34 At some point during their lives, animals are capable of movement. In the most commonly encountered animals, this stage is the adult, although some animals (corals) have sessile (nonmobile) adult phases and mobile juvenile forms.

35 Body Cavity and Development Acoelomate animals (like flatworms and flukes) do not have a coelom (or body cavity)Acoelomatecoelom Pseudocoelomate animals (like roundworms) have a body cavity but it does not develop from splitting of the mesoderm.Pseudocoelomatemesoderm Coelomate animals (humans, fish, shrimp) have a body cavity lined with mesoderm cells.


37 Coelomate

38 Coelomates are either protostomes or deuterostomes.protostomes deuterostomes Protostomes (first mouth) are coelomates whose embryonic development shows a blastopore associated with a mouth. Deuterostomes (second mouth) are coelomates whose embryonic development shows a blastopore associated with an anus, with a second opening forming the mouth (hence "second mouth").

39 Segmented Bodies Some animals have their bodies divided into segments. This allows them to specialize certain segments, such as for antennae, eyes, claws, etc. Humans, insects, and earthworms are examples of segmented animals.

40 Make a Chart to record notes! PhylumSymmetryBody planMain characteristics/example/picture Porifera asymetry acoelomate Most primitive animal, aquatic, diverse, sessile, diploblastic, Digestion is intra-cellular, filter feeders can reproduce asexually (by budding or from fragments) or sexuallyasexuallybuddingsexually examples: sponges Cnidarians radial Nematodes bilaateral


42 Sponges: The Phylum Porifera These asymmetrical animals have sac-like bodies that lack tissues, and are usually interpreted as representing the most primitive form of animals. Cells from fragmented sponges can reorganize/regenerate the sponge organism, something not possible with animals that have tissues. Most zoologists consider sponges as offshoots that represent an evolutionary dead- end. Sponges are aquatic, largely marine animals, with a great diversity in size, shape, and color.

43 Sponges (Phylum Porifera) Sponges are sessile, spending their lives anchored to a solid surface underwater. Most are marine although some live in fresh water. diploblastic; that is, the body wall is made of two layers of cells with a jellylike mesoglea between them; The body wall is perforated with pores (hence the name Porifera) through which water containing food particles is filtered. The water is drawn in through the pores by collar cells like those found in choanoflagellates.choanoflagellates Digestion is intra-cellular (inside the cells ). dispersed by small, free-swimming larvae; about 10,000 species known



46 Sponges can reproduce asexually (by budding or from fragments) or sexually. Sponges produce eggs and sperm that are released into a central cavity of the sponge, in which the zygote develops into a ciliated larva. The larval stage is able to move about while the adult is stationaryasexually buddingsexuallyzygote



49 Poriferans don't have mouths; instead, they have tiny pores in their outer walls through which water is drawn. Cells in the sponge walls filter goodies from the water as the water is pumped through the body and out other larger openings. The flow of water through the sponge is unidirectional, driven by the beating of flagella which line the surface of chambers connected by a series of canals. Sponge cells perform a variety of bodily functions and appear to be more independent of each other than are the cells of other animals.



52 Radial symmetry


54 Cnidarians are incredibly diverse in form, as evidenced by colonial siphonophores, massive medusae and corals, feathery hydroids, and box jellies with complex eyes.siphonophoresmedusaecorals hydroidsbox jelliescomplex eyes



57 The name Cnidaria comes from the Greek word "cnidos," which means stinging nettle. Casually touching many cnidarians will make it clear how they got their name when their nematocysts eject barbed threads tipped with poison.

58 There are four major groups of cnidarians: Anthozoa, which includes true corals, anemones, and sea pens; Cubozoa, the amazing box jellies with complex eyes and potent toxins; Hydrozoa, the most diverse group with siphonophores, hydroids, fire corals, and many medusae; and Scyphozoa, the true jellyfish. Anthozoa Cubozoa Hydrozoa Scyphozoa

59 The Phylum Cnidaria adult bodies having radial symmetry. aquatic, mostly all marine. have only the ectoderm and endoderm tissue layers. Members of this phylum are characterized by stinging cells, that eject a barbed thread and possibly a toxin. Only cnidarians' have cnidocytes, a specialized cell that contains a nematocyst, a fluid-filled capsule containing a long, spirally coiled hollow thread. When the trigger of the cnidocyte is touched, the nematocyst is discharged. Some threads merely trap a prey or predator, while others have spines that penetrate and inject paralyzing toxins.toxins


61 Cnidarians (Phylum Cnidaria) Characteristics: diploblastic; two layers of cells ectoderm and endoderm with a jellylike mesoglea between them; predominantly radial symmetry: body parts (e.g., tentacles) arranged in whorls. cnidoblasts: specialized cells that secrete a stinging capsule called a nematocyst. Food is taken through a mouth into the gastrovascular cavity. The cavity is also called a coelenteron and for many years the name of this phylum was Coelenterata. There is no anus. Sexual reproduction produces a free-swimming, ciliated larva called a planula.

62 The phylum contains about 10,000 species distributed in 3 classes: –Hydrozoa Although the freshwater hydra is a much-studied representative, it is not typical of the class. produce two body forms: the sessile polyp (like the hydra) and the free-floating medusa (which disperses the species) –Scyphozoans Jellyfishes (the medusa stage is dominant). The jelly of the medusa is a much- enlarged mesoglea. –Anthozoans Sea anemones and corals. Have only the polyp stage.


64 Two body forms occur: a mobile medusa and a sessile (not mobile) polypmedusapolyp


66 Class Anthozoa: Sea Anemones and Corals

67 Class Hydrozoa: Hydras and Portuguese Man-of-War (Physalia)

68 Class Schyphozoa: True Jellyfishes

69 Scientific Name Heteractis malu Comment s A sea anemone (Anthozoa) ReferenceFrom D. G. Fautin and G. R. Allen Field Guide to Anemonefishes and their Host Sea Anemones. Western Australia Museum. Creator photographed by Art Reed Specimen Condition Live Specimen Copyright © 1992 Western Australia Museum Scienti fic Name Aglantha digitale Comm ents A direct-developing holoplanktonic hydromedusa (Hydrozoa) that has no polyp. The gonads are visible through the transparent bell. Copyri ght © 1998 Claudia E. MillsClaudia E. Mills

70 Bilaterians bilateral symmetry All the remaining groups of animals belong in a clade whose members share:clade bilateral symmetry (hence the name); that is, dorsal- ventral and left-right axes triploblastic (three tissue layers: ectoderm, mesoderm, endoderm)three tissue layers HOX genes in one or more clusters with the genes within a cluster arranged in the same order as the body parts they affect.HOX genes The bilaterians contain two clades, the protostomes and the deuterostomes.

71 Bilateral Symmetry

72 Protostomes vs. Deuterostomes protostomes ("first mouth") and the deuterostomes ("second mouth").






78 Phylum Platyhelminthes Bilateral Symmetry and Cephalization The phylum as a whole has adult bilateral symmetry and cephalization (the development of a head with sensory organs, in most members). flatworms

79 Flatworms (Phylum Platyhelminthes) This phylum contains some 20,000 species distributed among three classes:

80 Turbellaria, free-living forms of which the planarian is a commonly-studied example. Planaria share with the other members of the phylum a flat, almost ribbon like, shape bilateral symmetry. The bilateral symmetry of planarians is associated with active locomotion –by secreting a layer of mucus underneath them and propelling themselves forward with the many cilia on their ventral surface. –and by swimming. a concentration of sense organs in the head called Cephalization. Planarians feed through a mouth on their ventral surface. It leads to an elaborate gastrovascular cavity. But there is no separate exit so undigested food has to leave by the mouth.

81 Trematoda, a group of parasitic lung flukes liver flukes and blood flukes (e.g., Schistosoma) All of these have at least two different stages in their life cycle, each parasitic in a different host one of which is usually a snail. The diagram gives the life cycle of the blood fluke, Schistosoma mansoni. Once within the alternate host, a snail, a single miracidium may produce as many as 200,000 infectious cercariae. Both sexes must infect the human if the cycle is to continue. With the increasing use of irrigation in tropical regions, the incidence of human infection is rising alarmingly.


83 Fasciola hepatica, a liver fluke, in a section of liver Image from a page at The Parasitology Images List by Peter Darben. Parasitology Images List

84 The Class Cestoda consists of the tapeworms If humans eat the meat of infected pigs or cattle and fail to cook it properly, they too become infected.

85 The Phylum Nemertea: Ribbon Worms The Phylum Rotifera


87 Roundworms (nematodes) are bilaterally symmetrical, worm-like organisms that are surrounded by a strong, flexible noncellular layer called a cuticle. Their body plan is simple.

88 A true coelom is lacking, instead, nematodes have a "pseudocoel" formed directly from the cavity of the blastula (rather than as a result of the division or folding of mesoderm). The cavity of the pseudocoel is small, being mostly filled with an intestine and oviducts or testes. A simple nervous system consists of a ring of nervous tissue around the pharynx that gives rise to dorsal and ventral nerve cords running the length of the body.

89 Nematodes are almost unbelievably abundant. One study reported around 90,000 individual nematodes in a single rotting apple. Another reported 236 species living in a few cubic centimeters of mud. The number of described species is around 12,000, but too little attention has been paid to these animals and the true number may be closer to 500,000.




93 Adult tape worm Hook worm

94 Roundworms (Phylum Nematoda) Features: A one-way digestive tract running from mouth to anus. A cavity between the digestive tract and the body wall. It develops from the blastocoel and is called a pseudocoelum. blastocoel Some 25,000 species have been identified but this may be less than 10% of the true number. Most are free-living; found in soil where they are important decomposers. Some are parasitic, including –hookworms (In 2003 the number of humans infected by hookworms was estimated at 740 million worldwide.); –pinworms; –Ascaris and –many parasites of commercially important plants like strawberries and oranges. Most are small although one that parasitizes whales reached 30 feet!

95 The Tube-within-a-tube Body Plan: Phylum Nematoda


97 Ascaris is a parasitic roundworm. These worms are unsegmented and have a smooth outside wall. They move by whip like motions. Mating produces eggs that mature in the soil, limiting most are to warmer climates. When eggs are swallowed, larvae burrow through the intestinal wall, moving to the liver, heart and/or lungs. Once within the lungs, larvae molt and, after 10 days, migrate up the windpipe to throat where they are swallowed. In the intestine, the mature worms mate and the female deposits eggs that are lost with the feces. Feces must reach the mouth of the next host to complete the life cycle, thus, proper sanitation is an important aspect to prevent infection.

98 Humans contract Trichinella (which causes the disease trichinosis) by eating raw pork containing encysted larvae. Mature female adults burrow into the wall of the small intestine. Live offspring are carried by the bloodstream to the skeletal muscles where they encyst. Religious dietary injunctions against eating pork may in part be a reflection of the prevalence of this disease in the Middle East.





103 Annelids (Phylum Annelidia) Characteristics: segmented; that is, their body is made up of repeating units. Although some structures, e.g., the digestive tract, run straight through, others like the excretory organs are repeated in each segment. The major nerve trunk runs along the ventral side. a large, fluid-filled coelom; It is lined with mesoderm and enables the internal organs to slide easily against one another making for easy locomotion. There are about 12,000 species known, distributed among the







110 CLAM


112 Mollusks (Phylum Mollusca) With 70,000 living species (perhaps only a third of the number out there), the mollusks must be counted as among the most successful animals on earth today.


114 Bivalvia. Two shells encase the body. Includes the clams, mussels, oysters, and scallops.

115 Gastropoda. Snails and slugs. Snails have a single shell ("univalves') while slugs have none.

116 Cephalopoda. This marine group includes the various species of octopus, squid, as well as the chambered nautilus. A record 28-foot octopus and 60-foot (18 m) squid make these the largest of all the invertebrates.

117 Scaphopoda. Marine, filter-feeding "tooth shells".

118 Amphineura. Includes the chitons, whose shell is made of 8 overlapping plates ("polyplacophora")

119 Monoplacophora. Until a live specimen was discovered in 1952, these animals were thought to have been extinct for millions of years. It has a single shell (hence the name) and, unlike the other mollusks, is segmented (as are its relatives the annelids).


121 Arthropods are invertebrates with jointed legs. They make up about 75% of all animals on Earth

122 Arthropods are divided into four major groups: insects; myriapods –(including centipedes and millipedes) arachnids –(including spiders, mites and scorpions) crustaceans –(including prawn and crabs).





127 Arthropods (Phylum Arthropoda) Some characteristics: Incredible diversity. Over a million living species have been identified so far more than all the other species of living things put together and this is probably only a fraction of them. Live in every possible habitat: fresh water, salt water, soil, even in the most forbidding regions of Antarctica and high mountains. A jointed external skeleton made of chitin, Segmented.chitin Pairs of jointed appendages; one pair to a segment used for locomotion, feeding, sensation, weaponry. Bilateral symmetry. Main nerve cord runs along the ventral side.


129 We shall look at four groups (subphyla): Crustacea Hexapoda (the insects) Myriapoda Chelicerata

130 Crustacea Head and thorax fused into a cephalothorax. At least 40,000 species. Most are aquatic, found in both fresh water and in the oceans. Includes crayfish, lobsters, barnacles, crabs, shrimp.

131 Hexapoda the insects Body segments grouped into head, thorax, and abdomen. Each of the 3 thoracic segments carries a pair of legs (hence the 6-legged "hexapoda") Many have wings, usually 2 pairs Gas exchange through a tracheal system. Nitrogenous waste is uric acid thus conserving water.uric acid Some 950,000 species, and this may be only 10% of the number out there. Dominate all habitats except for the oceans.

132 Myriapoda Some 13,000 species of centipedes and millipedes

133 Chelicerata Anterior segments fused into a cephalothorax. The first pair of appendages the chelicerae are used for feeding. There are no antennae. Includes: –Merostomata. The only member alive today is Limulus, the horseshoe "crab". –Arachnids (some 75,000 species) 8-legged scorpions, mites, ticks, spiders, daddy longlegs.

134 Book lungs in spiders

135 The Deuterostomes








143 Echinoderms (Phylum Echinodermata) Characteristics: radial symmetry. HOWEVER, their larvae have bilateral symmetry so the echinoderms probably evolved from bilaterally symmetrical ancestors water vascular system. Seawater is taken into a system of canals and is used to extend the many tube feet. These have suckers on their tips and aid the animal in attaching itself to solid surfaces. About 6,000 species all of them marine.


145 amphioxus in feeding position.

146 The pharynx is the anterior part of the digestive tract, just behind the mouth. A notochord is a cartilaginous rod that lies ventral to the hollow dorsal nerve cord in the chordate phyla.

147 Chordates (Phylum Chordata) During their embryonic development, all chordates pass through a stage called the pharyngula. a dorsal, tubular nerve cord ("1") running from anterior to posterior. At its anterior end, it becomes enlarged to form the brain. a flexible, rod like notochord ("2") that runs dorsal to the digestive tract and provides internal support. In vertebrate chordates, it is replaced by a vertebral column or backbone long before maturity. pairs of gill pouches. These lateral out-pockets of the pharynx are matched on the exterior by paired grooves. In aquatic chordates, one or more pairs of gill pouches break through to the exterior grooves, forming gill slits ("3"). These provide an exit for water taken in through the mouth and passed over the gills. a tail that extends behind the anus

148 4 main characteristics 1. Single, hollow nerve cord beneath dorsal surface; in vertebrates, it differentiates into brain and spinal cord 2. Notochord: flexible rod on the dorsal side of gut, present at one stage in all chordates; displaced in vertebrates by vertebral column that forms around the nerve cord 3. Pharyngeal slits (pouches) connect pharynx (between mouth and esophagus) with outside ? gills in sharks, fish; present in terrestrial animal embryos but disappear later except Eustachian tube (connecting throat and middle ear) 4. Postanal tail extends beyond anus; present at least in embryo; regresses into tail bone in humans

149 The vast majority of chordates have a skull enclosing their brain (Craniata), and all but one of these (the hagfish) convert their notochord into a vertebral column or backbone. These latter are the vertebrates

150 Urochordata This group, also called Tunicates includes animals known commonly as sea squirts). They are: marine sessile animals feed by filtering food particles from seawater taken in through one opening, or siphon, and squirted out the other.

151 Cephalochordata The representative member of this tiny subphylum of so-called lancelets is a small (5 cm), marine, fishlike creature called amphioxus (on the right). (For years its genus name was Amphioxus but that has now been replaced by the name Branchiostoma.) Amphioxus retains: a dorsal nerve cord notochord and gill slits

152 Organism Name Phylum Symmetry Diagram and description 1 Sponge Porifera asymmetry 2 Sea urchin Echinodermata radial 3 Starfish Echinodermata radial 4 Sea anemone Cnideria radial 5 Jelly fish Cnideria radial 6 Man of War Cnideria radial 7 Round worm nematoda bilateral 8 Earthworm Annelidia bilateral

153 Organism Name Phylum Symmetry Diagram and description 11 LeechAnnelidiabilateral 10 CrayfishArthropodaBilateral 11 SpiderArthropodabilateral 12 DragonflyArthropodabilateral 13 grasshopperArthropodabilateral 14 roachArthropodabilateral 15 Painted ladyArthropodabilateral 16 Water bugArthropodabilateral 17 Land snailmolluskabilateral


155 Test on invertebrate Animals 1. Invertebrates are animals without backbones. 2. The ancestors to invertebrate animals lived in water and were single celled organisms like protozoans. 3. Sponges belong to the phylum Porifera.

156 4. They have no tissues, organs or organ systems. Sponges are the simplest of the animals. 5. Sponges lack a certain structure to their body arrangement and are called asymmetrical. 6. Because sponges do not move around they are called sessile.

157 7. Cnidarians are named for the stinging cells that contain nematocysts and are used to capture food. 8. Jelly fish and corals are examples of cnidarians. 9. Roundworms belong to the phylum Nematoda and have a pseudocoelom or false body cavity.

158 10. Most roundworms are free living but many are parasites and cause disease to plants and animals that they infect. 11. Flatworms belong to the phylum Platyhelminthes and include planarians and tapeworms. 12. The body of a flat worm can be split into two sections from head to tail that are almost identical, this is called bilateral symmetry.

159 13. Because a flatworm has no body cavity it is called an acoelomate. 14. Slugs, snails, clams and squids are all members of the phylum Molluska. 15. Mollusks body plans are bilaterally symmetrical and have a body cavity called a coelom. 16. Mollusks can be grouped into classes. Match the class with an example. Gastropodsnail Bivalvescallop or clam Cephalopodoctopus

160 17. Segmented worms belong to the phylum Annelida. 18. Examples of annelids are earthworms and leaches. 19. Annelids have segmented bodies that are bilaterally symmetrical and have a coelom. 20. Earthworms have bristle structures on each segment to help them move called setae.

161 21. Food passes through the earthworms body from the mouth to the pharynx to the esophagus to the crop to the gizzard to the intestine. 22. Arthropods are animals with jointed appendages, bilateral symmetry, a coelom and a hard exoskeleton. 23. Arthropod means jointed appendage. 24. The exoskeleton is for protection.

162 25. Appendages are specialized to perform certain functions for the organism like the cheliped or claw for the crayfish. 26. There are many different types of arthropods. Examples of arthropods include spiders, millipedes, insects and crayfish. 27. Spiny skin is what Echinoderm means.

163 28. Echinodermata includes organisms that are radially symmetrical and have a coelom. 29. Examples of echinoderms are starfish, sea stars, sand dollars and sea cucumbers. 30. There is a group of invertebrates that are chordates. This means that they have a notochord which is a dorsal hollow nerve cord.

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