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Marine Invertebrates. Phylum Porifera: Sponges 1. Non-moving (sessile) animals 2. No nerves or muscles (no tissue differentiation) 3. Mostly marine 4. Filter feeders: Collect food particles from water
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Marine Invertebrates
Phylum Porifera: Sponges 1. Non-moving (sessile) animals 2. No nerves or muscles (no tissue differentiation) 3. Mostly marine 4. Filter feeders: Collect food particles from water 5. Most sponges are hermaphrodites. Hermaphrodites function as both male and female in sexual reproduction by producing eggs and sperm. **All other animals have true tissues
Animals probably evolved from colonial, flagellated protists, like this choanoflagellate colony.
Cnidarians • Polyp and medusa forms of cnidarians. • Radial symmetry with central digestive (gastrovascular) cavity. • One opening in the gastrovascular cavity serves as both mouth and anus. • Carnivores. • Phylum name comes from specialized cells called cnidocytes. • Cnidocytes are stinging cells used for defense and to capture prey.
Phylum Ctenophora • The Comb jellies • Resemble cnidarian medusas. • Use cilia for locomotion.
Phylum Platyhelminthes: Flatworms • Sizes range from microscopic up to 20 meters long (tapeworms). • Many are parasites.
Class Turbellaria (flatworms) • Mostly free-living (non-parasitic) • Feed on small animals, dead animals • Very flat for O2 exchange. They have no gas exchange organs.
Classes Trematoda Live as parasites Trematodes parasitize vertebrates. (For example, humans but often with intermediate hosts)
Class Cestoidea – Tapeworms • Live as parasites • Head contains suckers and hooks that lock onto the intestinal lining of the host. • The rest of the body is mostly units called proglottids that are sex organs. • Eggs transferred to new hosts by consuming fecal contaminated water.
Phylum Rotifera: Rotifers • Aquatic • Sizes range from 0.5 to 2 mm • Complete digestive tract
Lophophorate Phyla: Bryozoans, Phoronids, & Brachiopods All of these groups have a lophophore. The lophophore is a horseshoe shaped fold near the mouth that is surrounded by ciliated tentacles. Bryozoans resemble mosses. - They have a hard exoskeleton. - They are important as reef builders. Phoronids are marine worms. Brachiopods resemble clams.
Phylum Nemertea: Proboscis (ribbon) worms Up to 30 meters in length These worms have a hydraulically-operated proboscis that is used to capture prey. Closed circulatory system.
Phylum Mollusca: Mollusks Snails, clams, octopi, squids, oysters There are at least 150,000 known species All mollusks have similar body plans: a. Muscular foot b. Visceral mass with organs c. Mantle that secretes the shell
Bivalvia Shells divided into two parts. Gills are used for feeding and gas exchange. Example: Clams, oysters
Dreissena polymorpha Zebra mussel
Cephalopoda Rapid movement; well-developed nervous systems. Example: Octopus, squid, nautilus
Phylum Annelida: Segmented worms Sizes range from 1 mm to 3 meters in length. Each segment contains a pair of excretory tubes called metanephridia. Annelids are hermaphrodites that cross-fertilize. Three classes: a. Oligochaeta – earthworms b. Polychaeta – mostly marine c. Hirudinea – leeches