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Sponges are sessile and have a porous body and choanocytes

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1 Sponges are sessile and have a porous body and choanocytes
Sponges, phylum Porifera, live in both fresh and marine waters Sponges lack true tissues and organs Sponges are suspension feeders, capturing food particles suspended in the water that passes through their body Choanocytes, flagellated collar cells, generate a water current through the sponge and ingest suspended food Most sponges are hermaphrodites: Each individual functions as both male and female

2 Flagellum Food particles in mucus Choanocyte Choanocytes Collar Osculum Azure vase sponge (Callyspongia plicifera) Spongocoel Phagocytosis of food particles Amoebocyte Porocytes Spicules Epidermis Water flow Amoebocyte Mesohyl

3 Cnidarians have radial symmetry, a gastrovascular cavity, and cnidocytes
All animals except sponges belong to the clade Eumetazoa, animals with true tissues Phylum Cnidaria is one of the oldest groups in this clade Cnidarians have diversified into a wide range of both sessile and floating forms including jellies, corals, and hydras They exhibit a relatively simple diploblastic, radial body plan

4 The basic body plan of a cnidarian is a sac with a central digestive compartment, the gastrovascular cavity A single opening functions as mouth and anus There are two variations on the body plan: the sessile polyp and floating medusa

5 Mouth/anus Tentacle Polyp Medusa Gastrovascular cavity Gastrodermis Mesoglea Body stalk Epidermis Tentacle Mouth/anus

6 Cnidarians are carnivores that use tentacles to capture prey
The tentacles are armed with cnidocytes, unique cells that function in defense and capture of prey

7 Prey Tentacle “Trigger” Discharge of thread Nematocyst Coiled thread Cnidocyte

8 Scyphozoans (jellies)
Cubozoan (sea wasp) Anthozoan (sea anemone) Hydrozoans

9 Reproductive polyp Feeding polyp Medusa bud MEIOSIS Gonad Medusa SEXUAL REPRODUCTION Egg Sperm ASEXUAL REPRODUCTION (BUDDING) Portion of a colony of polyps FERTILIZATION Zygote Developing polyp Mature polyp Planula (larva) Key Haploid (n) 1 mm Diploid (2n)

10 Most animals have bilateral symmetry
The vast majority of animal species belong to the clade Bilateria, which consists of animals with bilateral symmetry and triploblastic development

11 Flatworms Members of phylum Platyhelminthes live in marine, freshwater, and damp terrestrial habitats They are flattened dorsoventrally and have a gastrovascular cavity Although flatworms undergo triploblastic development, they are acoelomates

12 Turbellarians Planarians have light-sensitive eyespots and centralized nerve nets The planarian nervous system is more complex and centralized than the nerve nets of cnidarians

13 Pharynx Gastrovascular cavity Eyespots Ganglia Ventral nerve cords

14 Trematodes Trematodes live as parasites in or on other animals
Trematodes that parasitize humans spend part of their lives in snail hosts

15 Mature flukes live in the blood vessels
of the human intestine Male Female 1 mm Larvae penetrate skin and blood vessels of humans. Blood flukes reproduce sexually in the human host. Fertilized eggs exit host in feces. Eggs develop in water into ciliated larvae. Larvae infect snails. Asexual reproduction within snail results in another type of motile larva. Snail host

16 Tapeworms are also parasitic and lack a digestive system
Proglottids with reproductive structures 200 µm Scolex Hooks Sucker

17 Rotifers Rotifers, phylum Rotifera, are tiny animals that inhabit fresh water, the ocean, and damp soil Rotifers are smaller than many protists but are truly multicellular and have specialized organ systems Rotifers have an alimentary canal: a digestive tube with a separate mouth and anus that lies within a fluid-filled pseudocoelom Rotifers reproduce by parthenogenesis, in which females produce offspring from unfertilized eggs

18 Molluscs have a muscular foot, a visceral mass, and a mantle
Phylum Mollusca includes snails and slugs, oysters and clams, and octopuses and squids Most molluscs are marine, though some inhabit fresh water and some are terrestrial Molluscs are soft-bodied animals, but most are protected by a hard shell All molluscs have a similar body plan with three main parts: Muscular foot, visceral mass and mantle

19 Visceral mass Coelom Heart Intestine Nephridium Gonads Mantle Stomach Radula Mantle cavity Shell Mouth Radula Anus Gill Mouth Nerve cords Foot Esophagus

20 Most molluscs have separate sexes with gonads located in the visceral mass
The life cycle of many molluscs includes a ciliated larval stage called a trochophore

21 There are four major classes of molluscs:
Polyplacophora (chitons) Gastropoda (snails and slugs) Bivalvia (clams, oysters, and other bivalves) Cephalopoda (squids, octopuses, cuttlefish, and chambered nautiluses)

22 Class Polyplacophora consists of the chitons, oval-shaped marine animals encased in an armor of eight dorsal plates

23 Gastropods About three-quarters of all living species of molluscs belong to class Gastropoda Most gastropods are marine, but many are freshwater and terrestrial species Most have a single, spiraled shell Slugs lack a shell or have a reduced shell The most distinctive characteristic of gastropods is torsion, which causes the animal’s anus and mantle to end up above its head

24 A land snail A sea slug. Nudibranchs, or sea slugs, lost their shell during their evolution.

25 Stomach Intestine Mantle cavity Anus Mouth

26 Bivalves Molluscs of class Bivalvia include many species of clams, oysters, mussels, and scallops They have a shell divided into two halves The mantle cavity of a bivalve contains gills that are used for feeding as well as gas exchange


28 Coelom Hinge area Mantle Gut Heart Adductor muscle Shell Anus Mouth Excurrent siphon Palp Water flow Foot Mantle cavity Incurrent siphon Gill

29 Cephalopods Class Cephalopoda includes squids and octopuses, carnivores with beak-like jaws surrounded by tentacles of their modified foot Most octopuses creep along the sea floor in search of prey Squids use their siphon to fire a jet of water, which allows them to swim very quickly One small group of shelled cephalopods, the nautiluses, survives today

30 Octopuses are considered among the most intelligent invertebrates.

31 Squids are speedy carnivores with beaklike jaws and well-developed eyes.

32 Chambered nautiluses are the only living cephalopods with an external shell.

33 Annelids are segmented worms
Annelids have bodies composed of a series of fused rings The phylum Annelida is divided into three classes: Oligochaeta (earthworms and their relatives) Polychaeta (polychaetes) Hirudinea (leeches)

34 Oligochaetes Oligochaetes (class Oligochaeta) are named for relatively sparse chaetae, bristles made of chitin They include the earthworms and a variety of aquatic species Earthworms eat through soil, extracting nutrients as the soil moves through the alimentary canal

35 Cuticle Epidermis Coelom Septum (partition between segments) Circular muscle Longitudinal muscle Metanephridium Anus Dorsal vessel Chaetae Intestine Ventral vessel Nerve cords Nephrostome Metanephridium Clitellum Esophagus Crop Pharynx Intestine Giant Australian earthworm Cerebral ganglia Gizzard Mouth Ventral nerve cords with segmental ganglia Subpharyngeal ganglion Circulatory system

36 Members of class Polychaetes have paddlelike parapodia that work as gills and aid in locomotion

37 Members of class Hirudinea are blood-sucking parasites, such as leeches

38 Nematodes are nonsegmented pseudocoelomates covered by a tough cuticle
Nematodes, or roundworms, are found in most aquatic habitats, in the soil, in moist tissues of plants, and in body fluids and tissues of animals The cylindrical bodies of nematodes (phylum Nematoda) are covered by a tough coat called a cuticle

39 Arthropods are segmented coelomates that have an exoskeleton and jointed appendages
Two out of every three known species of animals are arthropods Members of the phylum Arthropoda are found in nearly all habitats of the biosphere

40 General Characteristics of Arthropods
The diversity and success of arthropods are largely related to their segmentation, hard exoskeleton, and jointed appendages As arthropods evolved, the segments fused, and the appendages became more specialized The appendages of some living arthropods are modified for many different functions

41 Cephalothorax Abdomen Thorax Head Antennae (sensory reception) Swimming appendages (two sets located under abdomen Walking legs Pincer (defense) Mouthparts (feeding)

42 The body of an arthropod is completely covered by the cuticle, an exoskeleton made of chitin
When an arthropod grow, it molts its exoskeleton in a process called ecdysis Arthropods have an open circulatory system in which fluid called hemolymph is circulated into the spaces surrounding the tissues and organs A variety of organs specialized for gas exchange have evolved in arthropods

43 Molecular evidence suggests that living arthropods consist of four major lineages that diverged early in the phylum’s evolution: Cheliceriforms (sea spiders, horseshoe crabs, scorpions, ticks, mites, and spiders) Myriapods (centipedes and millipedes) Hexapods (insects and relatives) Crustaceans (crabs, lobsters, shrimps, barnacles, and many others)

44 Cheliceriforms Cheliceriforms, subphylum Cheliceriformes, are named for clawlike feeding appendages called chelicerae Most marine cheliceriforms are extinct, but some species survive today, including horseshoe crabs Most modern cheliceriforms are arachnids, which include spiders, scorpions, ticks, and mites Arachnids have an abdomen and a cephalothorax, which has six pairs of appendages, the most anterior of which are the chelicerae

45 Stomach Intestine Heart Brain Digestive gland Eyes Ovary Poison gland Anus Book lung Spinnerets Gonopore (exit for eggs) Chelicera Pedipalp Sperm receptacle Silk gland

46 Myriapods Subphylum Myriapoda includes millipedes and centipedes
Millipedes, class Diplopoda, have many legs Each trunk segment has two pairs of legs Centipedes, class Chilopoda, are carnivores with jaw-like mandibles They have one pair of legs per trunk segment

47 Insects Subphylum Hexapoda, insects and relatives, has more species than all other forms of life combined They live in almost every terrestrial habitat and in fresh water The internal anatomy of an insect includes several complex organ systems

48 Abdomen Thorax Head Compound eye Antennae Dorsal artery Crop Cerebral ganglion Anus Heart Vagina Malpighian tubules Ovary Tracheal tubes Mouthparts Nerve cords

49 Many insects undergo during their development metamorphosis
In incomplete metamorphosis, the young, called nymphs, resemble adults but are smaller and go through a series of molts until they reach full size Insects with complete metamorphosis have larval stages known by such names as maggot, grub, or caterpillar The larval stage looks entirely different from the adult stage

50 Larva (caterpillar) Pupa Pupa Emerging adult Adult

51 Crustaceans While arachnids and insects thrive on land, crustaceans, for the most part, have remained in marine and freshwater environments Crustaceans, subphylum Crustacea, typically have branched appendages that are extensively specialized for feeding and locomotion Decapods are all relatively large crustaceans and include lobsters, crabs, crayfish, and shrimp


53 Planktonic crustaceans include many species of copepods, which are among the most numerous of all animals

54 Barnacles are a group of mostly sessile crustaceans
They have a cuticle that is hardened into a shell

55 Echinoderms and chordates are deuterostomes
Sea stars and other echinoderms, phylum Echinodermata, may seem to have little in common with phylum Chordata, which includes the vertebrates

56 Chordates and echinoderms share characteristics of deuterostomes:
Radial cleavage Development of the coelom from the archenteron Formation of the mouth at the end of the embryo opposite the blastopore

57 Echinoderms Sea stars and most other echinoderms are slow-moving or sessile marine animals A thin, bumpy or spiny skin covers an endoskeleton of hard calcareous plates Unique to echinoderms is a water vascular system, a network of hydraulic canals branching into tube feet that function in locomotion, feeding, and gas exchange

58 Spine Stomach Anus Gills Central disk Madreporite Digestive glands Radial nerve Ring canal Gonads Ampulla Radial canal Podium Tube feet

59 A sea star (class Asteroidea)

60 A brittle star (class Ophiuroidea)

61 A sea urchin (class Echinoidea)

62 A feather star (class Crinoidea)

63 A sea cucumber (class Holothuroidea)

64 A sea daisy (class Concentricycloidea)

65 Animations and Videos Bozeman - Animal Characteristics
Overview of Invertebrates Life Cycle of a Cnidarian Chapter Quiz Questions – 1 Chapter Quiz Questions – 2

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