Biol 152 1st Edition Lecture 11I. Protostomes A. Phylum Nematoda (Roundworms)1. Small, cylindrical worms, free living2. Many are parasites that infect plants and animals 3. Sense organs and a primitive brain found behind the mouth B. Phylum Roitifera 1. Bilaterally symmetrical 2. 2 cell layers, tissues, and organs 3. Pseudo coelom 4. Gut with anus5. External layer of chitin called a lorica6. Brain and paired nerves 7. No circulatory or respiratory organs 8. Mostly pathogenic, otherwise sexual 9. Feed on bacteria, Protista, or are parasitic C. Phylum Gastrotricha1. Bilaterally symmetrical 2. 2 cell layers, tissues, and organs 3. Gut with a subterminal anus 4. Nervous system with ganglia 5. No circulatory system These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.6. Feed on bacteria, fungi, and protists D. Protostome Coelomates1. Prevents muscle movement from interfering with activity of the digestive and circulatory systems2. It provides a hydrostatic skeleton space against which muscles can operate 3. It provides protected space for sperm and ova production E. Phylum Mollusca1. A soft body with organs responsible for excretion, digestion and respiration.2. Body plan including a foot (for sensing and digging) a mantle (secretes a shell in most mollusks), a mantle cavity (contains breathing organs) and a visceral mass in which the intestinal tract, reproductive and excretory organs lie.F. Class Bivalva1. Include oysters, scallops, mussels and other mollusks with 2 shells.2. Most sedentary; some, like clams, can use their muscular foot to move about in their environment.G. Class Gastropoda1. Include snails, slugs, abalone, whelks, conches and limpets.2. Have a twisted body plan with well-developed heads.3. Some contain a single shell whereas others completely lack shells.H. Class Cephalopoda1. Include chambered nautiluses, squids and octopods.2. Lack an external shell (with the exception of the chamberedNautilus).3. The foot has evolved into tentacles which surround the mouth.4. Of all the mollusks, cephalopods are thought to be the mostIntelligent.The octopus has the most sophisticated brain of any invertebrate.I. Phylum Annelida1. Have long segmented bodies, specialized excretory organs and a closed circulatory system.2. Polychaeta (free-living bristle worms);3. Oligochaeta (earthworms);4. Hirudinea (leeches).J. Class Polychaeta 1. Include plumed worms, scale worms, clamworms, peacock worms, and sea mice.2. Each segment on the organism contains a pair of parapodia which are used for movement and respiration.3. Reproduce sexually and have separate male and female sexes.K. Class Olygocheta1. Include the common earthworm.2. Segments lack the parapodia found in polychaetes.3. Most are hermaphroditic and sexually reproduce by transferring sperm to a