Animal Embryological Development

UNIT 12: INVERTEBRATES

3 Germ Layers

Evolution

Phylogeny

Deriv

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PARAZOA (No True Tissue)Phylum Porifera

SessilePorous Bodies

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

RADIATA (Radial Symmetry)Diploblastic (Ectoderm and Endoderm) 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

Phylum Platyhelminthes (Flatworms)BILATERIA (Bilateral Symmetry)Triploblastic (Endo-, Ecto-, Mesoderm)Acoelemates (No Body Cavity)

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

True muscle tissueLack a digestive tract

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

Head (cephalized)Pair of eyespots

SmellLearn to modify their responses to stimuliHermaphrodites, copulating

BILATERIATriploblasticPseudocoelomates (False Body Cavity)

Phylum Rotifera (Rotifers)

JawsCrowns of ciliaComplete digestive tractMouth and anus

Some Parthenogenesis (all females)

Some degenerate males (sperm donors)

YouTube - Sponge Feeding.movYouTube - Sponge Reproduction.movYouTube - Sea Sponges Under The Sea

YouTube - Cnidarian Eating.movYouTube - Cnidaria Ability To Move.mov

YouTube - Planarian Regeneration Part 1.movYouTube - Planarian Regeneration Part 2.mov

Sponges Jellyfish and Sea Anemone

Phylum Mollusca BILATERIATriploblasticCoelomate (True Body Cavity)PROTOSTOMIA (Coelom From Cell Masses)

Snails and Slugs (land), Oysters, Clams, Octopuses and SquidsMost have hard shell made of calcium carbonate

GillsRadula to scrape up food

Open circulatory system Dorsal heart Circulatory fluid (hemolymph) Arteries

Excretory organs (nephridia)

Nerve cords

Most separate sexes, with gonads (ovaries or testes)

Closed circulatory systemComplex brain

Phylum Annelida (segmented worms)

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)

Earthworms, Leaches

Segmentation

Phylum Nematoda (round worms)

Nonsegmented pseudocoelomatesTough cuticle covering (exoskeleton)Molting, or ecdysisComplete digestive tractNo circulatory system

Separate sexesInternal fertilization

Pinworms, Hookworms

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

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

Muscular footVisceral massMantle

BILATERIATriploblasticCoelomatePROTOSTOMIA

BILATERIATriploblasticPseudocoelomate

Phylum Arthropoda

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)

BILATERIATriploblasticCoelomatePROTOSTOMIA

Insects, Spiders, Crustaceans, Scorpions, Centipedes, Millipedes, Ticks, Mites

Phylum Echinodermata

Water vascular system and secondary radial anatomy

Sessile or slow-moving animalsEndoskeletonWater vascular systemTube feet

Metamorphosis from bilateral larvae

Sea Stars, Sea Urchins, Sand Dollars

Regeneration

Phylum Chordata (Subphylum Vertebrata)Radial SymmetryTriploblasticCoelomateDEUTERSTOMIA

BILATERIATriploblasticCoelomateDEUTEROSTOMIA

FishAmphibiansReptilesBirdsMammals

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