Chapter 35

Section 35.1 Video

 Means “soft body”  Most marine, some freshwater, a few terrestrial

TerrestrialFresh Water Marine

 Definition: a body cavity that is completely lined by mesoderm and contains internal organs  Found in the following phlya:  Mollusca (clams)  Arthropoda (crayfish)  Echinodermata (starfish)  Chordata (humans)  Annelida (earthworms)

 Trochophore: larval stage of development for aquatic mollusks and annelids  Use cilia for swimming and feeding  Some have a hard shell for protection

 Body divided into 2 main section: head- foot & visceral mass:  Head-foot: head (mouth, sensory structures) and foot (locomotion)  Visceral mass: heart & digestive, excretion, and reproductive organs  Covered by the mantle

 Mantle: layer of epidermis that excretes a hard shell of calcium carbonate  Mantle cavity: space between mantle and visceral mass that protects the gills  Ganglia: clustered nerve cells that control locomotion & feeding  Radula: flexible, tongue-like strip of tissue covered with abrasive teeth

Video

radula – rasping “tongue” of chitin

1. Class Gastropoda 2. Class Cephalopoda 3. Class Bivalvia

(Snails, nudibranchs, cowries, whelks)

 Largest and most diverse group of mollusks  Examples: snails, abalones, conchs, slugs  Locomotion: wavelike muscular contractions on mucus slime trail  Can withdraw head into mantle cavity when threatened Video

 Hemolymph: circulatory fluid  Hemocoel: fluid filled spaces  A.k.a. blood cavity

 tentacles- sense touch & have eyes on ends  respire with gills (aquatic) or exposed blood vessels (terrestrial) by diffusion  we eat muscular foot “escargot”

shoot, then inseminate (mucus paralyzes female reproductive tract) successful darters double success

 Examples: octopuses, squids, cuttlefishes, chambered nautiluses  Marine animals, free swimming  Meaning “head-foot”

 Tentacles have large suction cups  Largest invertebrate brain  Highly advanced eyes similar to humans  Closed circulatory system  Many release dark, inky fluid when alarmed  Many have pigment cells called chromatophores for camouflage Video

Squid, chambered nautilus, cuttlefish, octopus

 Examples: clams, oysters, mussels, scallops  All have a two part shell connected by hinge closed by adductor muscles  aged by shell rings  sedintary  filter feeders Video

 2 siphons at the posterior end:  Incurrent siphon = intake of water & food  Excurrent siphon = output of water & wastes  Clams dig in the soil so only their siphons stick out  Filters about 3 quarts an hour! Video

 Calcium carbonate secretion around a foreign object  Protection of the soft visceral mass  Made by the mantle (just like the shell)

 protective outer layer   ///////////// prismatic layer  pearly layer

He Was Shellfish

Body parts you MUST identify & show me during the lab:  Umbo  Valves (shells)  Mantle  Gills  Incurrent & excurrent siphons  Palps & mouth  Digestive gland  Intestine  Gonads  Heart

 clam Oldest part

ANTERIOR POSTERIOR VENTRAL DORSAL

Section 35.2

 Examples: earthworms, leeches  Annelid means “Little rings”  Segmentation allows for division of labor  Bilateral symmetry  Live in freshwater, marine water, and terrestrial environments

 Setae: external bristles  Parapodia: fleshy protrusions on outside of body  Number of setae and parapodia divides this phylum into three class: 1. Class Polychaeta 2. Class Hirudinea 3. Class Oligochaeta

 “Many bristles”  Number of setae and parapodia  Have anetennae & specialized mouth parts  Most are marine animals  Trochophore larvae  Predatory  Largest class of annelids Video

 Smallest class of annelids  Example: leeches  Live in calm freshwater & moist vegetation  No setae or parapodia  Most are carnivores & some are parasitic  Secrete anaestheic & anticlotting factors  Ingest 10 times it own weight in blood!

 “Few bristles”  Few setae and no parapodia  Live in soil or freshwater  Example: earthworms

 Divided into over 100 segments  Movement:  Anchor middle segments with setae  Contract muscles in front  Elongation of anterior  Setae of anterior grip ground  Pull posterior forward

 Ingest soil as they burrow  Digestion path: mouth  esophagus  crop (temp. storage)  gizzard (releases & breaks up organic matter)  long intestine (absorption of nutrients)  anus

 Closed circulatory system  Ventral (toward posterior) & dorsal (toward anterior) vessels  Aortic arches link ventral and dorsal vessels

 Respiration: diffusion of oxygen and carbon dioxide via moist skin  Secretion of mucus to keep moist  Excretion: via nephridia (excretory tubules in every segment except first three)

 Chain of ganglia connected by a ventral nerve cord  Each segment has a single ganglia  Brain = fused ganglia  Simple sensory skills  Light  Touch  Chemicals  temperature

 Hermaphrodites  Cannot fertilize own self  Mating: press ventral surfaces together, anterior ends pointed opposite directions  Setae hold worms together  Mucus secretion from clitellum  Each worm injects sperm into mucus  Sperm going into seminal receptacles of other worm  Several days later chitin tube forms picking up eggs & stored sperm  fertilization  Young worms develop inside tube and hatch 2-3 weeks later

 Decomposers of leaves and organic matter  Recycle nutrients  Release natural fertilizers (waste)  Aerates the soil