Chapter 33 n Invertebrates

Parazoa n Invertebrates: animals without backbones n Closest lineage to protists n Loose federation of cells (unspecialized); no tissues n Phylum: Porifera (sponges)

Phylum: Porifera (“pore bearer”) n Sessile (attached to bottom), does not move n Spongocoel (central cavity) n Osculum (large opening) n Choanocytes (flagellated collar cells) n Hermaphroditic (produce both sperm and eggs)

The Radiata, I n Diploblastic n Radial symmetry n Phy: Cnidaria (hydra, jellies, sea anemones, corals) n No mesoderm; GVC gastrovascular cavity (sac with a central digestive cavity) n Hydrostatic skeleton (fluid held under pressure) n Polyps and medusa n Cnidocytes (cells used for defense and prey capture) n Nematocysts (stinging capsule)

The Radiata, II n Phylu: Ctenophora (comb jellies) n 8 rows of comblike plates of fused cilia (largest animals that use cilia for locomotion) n Tentacles with colloblasts (adhesive structures that capture prey)

Eumetazoa: The Acoelomates n Phylum: Platyhelminthes (flatworms, flukes, tapeworms) n Bilateral; no body cavity n Predators, scavengers, parasites n Triplobastic; mesoderm but, GVC with only one opening n Some cephalization n Many pathogens (Schistosoma, Cestodidias)

Eumetazoa: Pseudocoelomates, I n Body cavity partially derived from mesodermally derived tissue n Phy: Rotifera n 1st with a complete digestive tract n Hydrostatic skeleton n Parthenogenesis: type of reproduction in which females produce offspring from unfertilized eggs

Eumetazoa: Pseudocoelomates, II n Phylum: Nematoda (roundworms) n Very widespread group of animals (900,000 sp. ?) n Cuticle (tough exoskeleton) n Decomposition and nutrient cycling n Complete digestive track; no circulatory system n Trichinella spiralis

The Coelomates: Protostomes, I n Phylogenetics debated…. n Phy: Nemertea (proboscis and ribbon worms) n Complete digestion and closed circulatory system (blood) n Phy: the lophophorates (sea mats, tube worms, lamp shells) n Lophophore: Circular shaped body fold with ciliated tentacles around the mouth

The Coelomates: Protostomes, II n Phylum: Mollusca (snails, slugs, squid, octopus, clams, oysters, chiton) n Soft body protected by a hard shell of calcium carbonate n Foot (movement), visceral mass (internal organs); mantle (secretes shell); radula (rasp-like scraping organ) n Ciliated trochophore larvae (related to Annelida?)

The Coelomates: Protostomes, III n Phylum: Annelida (earthworms, leeches, marine worms) n True body segmentation (specialization of body regions) n Closed circulatory system n Metanephridia: excretory tubes n “Brainlike” cerebral ganglia n Hermaphrodites, but cross- fertilize

The Coelomates: Protostomes, IV n Phylum: Arthropoda trilobites (extinct); crustaceans (crabs, lobsters, shrimps); spiders, scorpions, ticks (arachnids); insects (entomology) n 2 out of every 3 organisms (most successful of all phyla) n Segmentation, hard exoskeleton (cuticle)~ molting, jointed appendages; open circulatory system (hemolymph); extensive cephalization =NGFDAA4g8Ew

Insect characteristics n Outnumber all other forms of life combined n Malpighian tubules: outpocketings of the digestive tract (excretion) n Tracheal system: branched tubes that infiltrate the body (gas exchange) n Metamorphosis…... nincomplete: young resemble adults, then molt into adulthood (grasshoppers) ncomplete: larval stages (looks different than adult); larva to adult through pupal stage

The Coelomates: Deuterostomes, I n Phylum: Echinodermata (sea stars, sea urchins, sand dollars, sea lilies, sea cucumbers, sea daisies) n Spiny skin; sessile or slow moving n Often pentaradial n Water vascular system by hydraulic canals (tube feet)