Chapter 34 Invertebrates PDF

CHPT 34 -- INVERTEBRATES NOTES Phylum CTENOPHORA - The comb jellies - First animal phylum to diverge from other animals - All marine, very abundant - Cilia for locomotion, Cilia are arranged into combs - Most have 2 long tentacles w/ sticky hairs - Have a gastrovascular cavity, ut...

CHPT 34 -- INVERTEBRATES NOTES Phylum CTENOPHORA - The comb jellies - First animal phylum to diverge from other animals - All marine, very abundant - Cilia for locomotion, Cilia are arranged into combs - Most have 2 long tentacles w/ sticky hairs - Have a gastrovascular cavity, utilized for digestion & circulation of digested nutrients - Hermaphrodites, have both male & female reproductive organs - Most are bioluminescent - Embryonic development & nervous system are unique - Mesoderm germ layer forms in a diff manner than in bilateral animals Phylum PORIFERA - The sponges - Mostly marine - Most have no symmetry - No tissues, probably a degenerative condition - Adults are SESSILE, stay anchored in 1 place - Sponges are filter feeders (suspension feeders), filtering particular matter and tiny plankton for food - Have many specialized cells - Flagellated choanocytes (collar cells) draw water through pore cells into the sponge - Amoebocytes absorb food from choanocytes, digest the food, and distribute the digested nutrients to the other cells - INTRAcellular digestion -- digestion in the cells, intra cellular digestion limits the size of the food - Sponges have a inner + outer layer of cells w/ gelatinous material in between - Most are hermaphrodites - Can produce asexually AND sexually - Contain a tough protein (spongin) - Many produce sharp SPICULES composed of silica/calcium carbonate/protein Phylum CNIDARIA - Jellyfish, corals, hydras, sea anemones, box jellies, others - Radial symmetry - Have 2 layers of tissue, ecto and endoderm - Mostly marine, some live in freshwater - Sac-lice bodies w/ a gastrovascular cavity - Have a jelly-like acellular material (mesoglea) between the 2 layers of tissue - Have cells called CNIDOCYTES that contain NEMATOCYTES that release venom through a tube - Have muscle-like (not actual muscles, don't have a mesoderm) fibers + a simple nerve net - Polyps -- cylindrical shape, sessile - Medusa -- flattened, rounded, free swimming - Polyps are sessile and reproduce asexually by producing medusae by budding - Medusae are free-swimming and reproduce sexually Phylum PLATYHELMINTHES - Flatworms - Acoelomates - Includes free-living & parasitic species - Have a gastrovascular tract w/ a single opening - Free-living forms include the well known planarians - Most have a distinct head + ventral nerve chords - Flukes are parasites - Schistosoma -- blood flukes - Tapeworms- parasites w/ no digestive tract, they absorb food. Have hooks to hook onto the host's intestinal walls Phylum ROTIFERA - Rotifers - Very small - Most live in fresh water - Pseudocoelomates - Have a crown of cilia that directs food into their mouth - Have jaws to grind food - Have a COMPLETE DIGESTIVE TRACT, w/ a complete mouth + anus Phylum NEMERTEA - Ribbon or proboscis worms - Coelomates - Have a complete digestive tract - Have a CLOSED circulatory system, blood is contained in vessels - Some are venemous Phylum MOLLUSCA - Includes snails, slugs, oysters, clams, chitons, octopuses, squid, and many more - \> 100k living species - Coelomates -- protostomes - Mostly marine, some in freshwater, some are terrestrial - Have soft bodies, many have a protective shell of calcium carbonate - Mollusk body has a muscular foot - Visceral mass -- contains most of the organs - Mantle -- a fold of tissue over the visceral mass, secretes the shell - Radula -- a rasping feeding organ found in many (not all) mollusks - MOST mollusks have an OPEN circulatory system, w/ their hemolymph (blood) directly bathing their organs - Have ventral nerve cords - There are 8 classes of mollusks - Snails, slugs - Clams, oysters, mussels, scallops - Mostly sessile - Filter feeders - Squids, octopuses, cuttlefish, and nautiluses - Most have internal shells - Have a CLOSED CIRCULATORY SYSTEM - Have a complex brain - Chitons - 8-plated shells Phylum ANNELIDA - Segmented worms - Earthworms, leaches, tubeworms, polychaete worms - Coelomates -- protostomes - CLOSED CIRCULATROY SYSTEM - metanephridia are paired excretory tubules located in each segment - have brain-like cerebral ganglia - earthworms are CROSS-FERTILIZING hermaphrodites - tube-worms are sessile as adults - leaches have a history in medicine - polychaetes are marine worms w/ parapodia (structures that look like legs) Phylum NEMATODA - UNSEGMENTED round worms - Pseudocoelomates - Found in aquatic habitats, in soil, and as plant/animal parasites - Very abundant - Could be as many as 100k species - Most are microscopic - Plant parasites are of major economic importance Phylum ARTHROPODA - Jointed feet - Crustaceans, spiders, insects, millipedes, centipedes, many others - Coelomates -- protostomes - At LEAST 1 million named species, most likely several million species in total - Have jointed legs, a hard exoskeleton, and segmentation - Exoskeleton: cuticle of arthropods; made of chitin and protein; provides protection, water resistance, something for muscles to work against - Molting: process where exoskeleton is grown out of - Many of their sensor organs = concentrated on their heads - Have an OPEN circulatory system - Onychophorans: walking worms, may resemble arthropod ancestors 1. Chelicerata -- arachnids, sea spiders, horseshoe crabs, eurypterids - Chelicerae: feeding appendages - Have no antennae, have simple eyes (1 lens), most fall under Class Arachnida - Arachnids include spiders, harvestmen, scorpions, ticks, mites - Most have 2 major body regions, w/ 4 pairs of legs - Most spiders utilize book lungs for respiration 2. Myriapoda -- centipedes, millipedes - Have antennae (1 pair), mandibles - Multi-legged, worm-like, more "primitive" than insects - Class -- Diplopoda - Millipedes - 2 pairs of legs/segment - Class -- Chilopoda - Centipedes - 1 pair of legs/segment - Carnivorous - Have claws that inject venom into prey 3. Crustacea -- crabs, lobsters, shrimp, barnacles, pill bugs - Have many heavily modified appendages - Have 2 pairs of antennae - 3/more appendages are modified as mouth parts - Most have gills for respiration - Krill = very important part of marine food chain - Important members of zooplankton (animal plankton) of marine + freshwaters 4. Hexapoda -- mostly insects - Class -- Insecta - More species than all other animals combined - Many have 2 pairs of wings - Only invertebrates that can fly - Have 3 body regions, head, thorax, abdomen - Have 3 pairs of legs - Have 1 pair antennae - Have 2 ventral nerve chords - Have a trachea (chitin-lined tube in the insect body) for respiration - Malpighian tubules = for excretion - Many insects have compound eyes (w/ many lenses) Phylum ECHINODERMATA - Spiny skin animals - Deuterostomes - Starfish, brittle stars, sea urchins, sand dollars, sea lilies/cucumbers - Have a hard skeleton covered w/ think skin - Radial symmetry as adults - Have WATER VASCULAR SYSTEM, hydraulic canals connected to tube feet - Tube feet can generate suction - Tube feet are used for locomotion, feeding, and respiration - Have a nervous system but there is no brain - Larvae are bilateral - Most closely related to our own Phyla Phylum HEMICHORDATA - Marine worms - Related to echinoderms + chordates - Some are burrowing sediment feeders, some are colonial filter feeders - Have most of the features of Phylum Chordata - Acorn worms - USED to be classified as chordates BILATERAL ANIMALS - 3 clades of bilateral animals - Lophotrocozoa & ecdysozoa are protostomes 1. Lophotrocozoa - Includes flatworms, rotifers, bryozoans, annelids, others - Posses specialized feeding structures (lophophores) - Distinct larval stage (trochophore) Lophophorate Phyla -- bryozoans, phoronids, brachiopods - All have a ciliated feeding structure called the lophophore - USED to be considered deuterostomes bcz of their development - Molecular evidence suggests they are more closely related to protostomes 2. Ecdysozoa - Nematodes and arthropods - Exhibit ECDYSIS, a periodic molting of a cuticle, a non-living cover offering support + protection 3. Deuterostomia - Include echinoderms, chordates, others - Share similar pattern of development METAMORPHOSIS Incomplete metamorphosis - The young (nymphs) look like small adults but cannot fly/reproduce - Go through several molts Complete metamorphosis - Larval stages - Transforms to adult during pupal stage Phylum TARDIGRADA - Water bears/ moss piglets - Most are less than 1mm long - Segmented - 4 pairs of unjointed legs, usually ending in claws - OPEN CIRCULATORY system - Reproduce sexually + asexually - Prefer wet habitats, often found in a film of water on mosses + lichen - Feed on body fluids or cells contents of plant cells/algae/small invertebrates - World's toughest animals, are resistant to extreme temps/pressure/impacts/radiation - Can suspend their metabolism (cryptobiosis), sometimes for 30+ years when they get dehydrated