CHAPTER 33INVERTEBRATES

PARAZOA Phylum Porifera

SessilePorous Bodies

Filter/ Suspension Feeders (pump water) Color - symbiotic algaeHermaphrodites Regeneration

RADIATA Phylum Cnidaria

Sac with a central digestive compartmentSessile polyp and the floating medusa

Tentacles (capture prey)

Stinging capsules

Muscles and nerves (simple)

No brainNoncentralized nerve net

Acoelemates Phylum Platyhelminthes (flatworms)

BILATERIA

Free-living formsSome parasites (tapeworm/fluke)Flattened dorsoventrally

Mesoderm (triploblastic)True muscle tissueLack a digestive tract

Lack organs specialized for gas exchange and circulationOsmoregulatory (pharynx opening)

Head (cephalized)Pair of eyespotsSmellLearn to modify their responses to stimuliHermaphrodites, copulating

BILATERIA Pseudocoelemates Phylum Rotifera

JawsCrowns of ciliaComplete digestive tractMouth and anus

Some Parthenogenesis (all females)

Some degenerate males (sperm donors)

Sponges Sea Anemone, Jellies

Tapeworm, Flukes

Central Digestive CompartmentSimple “Muscle and Nerve”

True Muscle TissueNerve Cord/ GangliaCephalization

Complete Digestive Tract

??

PSEUDOCEOLOMATESPhylum Nematoda (round worms) Pinworm, hookworm

Nonsegmented pseudocoelomatesTough cuticle covering (exoskeleton)

Molting, or ecdysis

Complete digestive tractNo circulatory system

Separate sexesInternal fertilization

YouTube - Roundworm inside cat's intestineYouTube - Parasites Eating Us Alive - Part 2YouTube - Parasite Monsters Inside Me - Part 1YouTube - Monsters Inside Me: Toddler Under AttackYouTube - Monsters Inside Me- Pork TapewormYouTube - Removing Intestinal Worms and Parasites from a 3 Year Old

PROTOSTOMIA Phylum MolluscaSnails and slugs (land), oysters, clams, octopuses and squids

Most have hard shell made of calcium carbonateMuscular footVisceral massMantle

GillsRadula to scrape up food

Nerve cords

Open circulatory system Dorsal heart Circulatory fluid (hemolymph) Arteries

Excretory organs (nephridia)

Most separate sexes, with gonads (ovaries or testes)

complex brain

closed circulatory system

YouTube - Wow! Giant octopus - extreme animals - BBC wildlifeYouTube - Cuttlefish: Chameleons of the Sea

Class:Cephalopoda

PROTOSTOMIAPhylum Annelida (segmented worms)

Earthworm, leachesCoelom Segmentation

Digestive system with specialized regions

Closed circulatory system

Blood pumping vessels

Brainlike pair of cerebral ganglia

Pair of nerve cords

Hermaphrodites, but they cross-fertilize

Regeneration (asexual)

Phylum: ArthropodaPROTOSTOMIA

Segmented coelomatesExoskeletons (cuticle/chiton)Jointed appendages

Two out of every three organisms known are arthropodsNearly all habitats

modified for walking, feeding, sensory reception, copulation, and defense

Molting (ecdysis) Well-developed sensory organs (sight, smell, touch)Cephalization is extensiveOpen circulatory systems (hemolymph) Heart (arteries and spaces called sinuses)Specialized gas exchange (gills/ trachea)

Antenna surface

Eyelash

DEUTEROSTOMIA Phylum Echinodermata

Water vascular system and secondary Radial anatomy

Sessile or slow-moving animalsEndoskeletonWater vascular system

Tube feetMetamorphosis from bilateral larvae

Sea Stars, Sea Urchins, Sand Dollars

Regeneration

Phylum ChordataDEUTEROSTOMIA Two subphyla of invertebrate animals plus the subphylum Vertebrata, the animals with backbones

Central Digestive CompartmentSimple “Muscle and Nerve”

True Muscle TissueNerve Cord/ GangliaCephalization

Complete Digestive Tract

??

ExoskeletonInternal Fertilization

Open circulatory system Dorsal heart Circulatory fluid (hemolymph) ArteriesExcretory OrgansGonadsCephalopods Complex Brains Closed Circulatory System

SegmentationDigestive system with specialized regionsClosed Circulatory System

Jointed appendagesSpecialized gas exchange Well-developed sensory organs Cephalization is extensive

Endoskeleton

Summary the animal phyla we have discussed in this chapter.

Choanocytes (collar cells--unique flagellated cells that ingest bacteria and tiny food particles); cells tend to be totipotent (retain zygote’s potential to form the whole animal)

Unique stinging structures (cnidae), each housed in a specialized cell (cnidocyte); gastrovascular cavity (incomplete digestive tract with a mouth but no anus)

Colloblasts (adhesive structures) for prey capture; eight rows of comblike ciliary plates; gastrovascular cavity

Dorsoventrally flattened, unsegmented acoelomates; gastrovascular cavity or no disgestive tract

Pseudocoelomates with complete digestive tracts; jaws in pharynx structures (trophi); head with a cilated crown (corona); no circulatory system

Coelomates with lophophore (feeding structure bearing cilated tentacles)

Unique anterior proboscis surrounded by fluid-filled cavity (rhynchocoel); complete digestive tract (mouth and anus); circulatory system with closed vessels

Coelomates with three main body parts (muscular foot, visceral mass, mantle); coelom reduced; main body cavity is a hemocoel

Coelomates with body wall and internal organs (except digestive tract) segmented

Cylindrical, unsegmented pseudocoelomates with tapered ends; no circulatory system

Coelomates with segmented body, jointed appendages, exoskeleton from ectoderm

Coelomates with secondary radial anatomy (larvae bilateral; adults radial); unique water vascular system; endoskeleton

Coelomates with notochord; dorsal hollow nerve cord; pharyngeal slits; muscular postanal tail