Chapter 10 Mollusks, Arthropods, Echinoderms

Mollusks Characteristics of Mollusks *Invertebrates *Often protected by a hard outer shell *Soft body *Thin layer of tissue called a mantle that covers its internal organs *Organ called a foot

Characteristics cont. Body Structure Bilateral symmetry Digestive system with two openings Internal organs located together in one area Circulatory System Most have open circulatory system Obtaining Oxygen Gills-organs that remove oxygen from the water Cilia helps move water over the gills

Gastropods-Snails and Slugs Largest group of Mollusks Have a single external shell or no shell at all Carnivores, herbivores, and scavengers Radula-a flexible ribbon of tiny teeth to obtain food Usually move creeping along on a broad foot

Bivalves-oysters, clams, scallops and mussels Bivalves-two shells held together by hinges and strong muscles Filter feed (omnivores) Swim or float as larva, often stationary as adults Produce pearly coat around sand to prevent irritation. A pearl is the result.

Cephalopods-Octopuses, squids, and nautiluses Ocean dwelling mollusk whose foot is adapted to form tentacles around its mouth Not all have shells Have a closed circulatory system Carnivores--captures prey using its muscular tentacles Tentacles-very sensitive, can taste as well as touch Large eyes and excellent vision, large brains Swim using jet propulsion

Masters of Camouflage & escaping prey

Arthropods- “Jointed appendages” Invertebrates-no backbone Segmented bodies Exoskeleton-outer skeleton Antenna (most arthropods have them)- appendage that contains sense organs

Crustaceans Body sections in 2 or 3, five or more pairs of legs, and two pairs of antennae Most have gills to obtain oxygen Some are scavengers, predators, herbivores Develop into adults through metamorphosis

Characteristics of Echinoderms Invertebrates Endoskeletons-internal skeleton Fluid-filled tubes called a water vascular system Radial Symmetry Tube Feet-squeezing together forces water into the structure. They are sticky and used for movement Sexually reproduce where water and sperm meet, usually in the water, to form a tiny larva

Diversity of Echinoderms Sea stars (Starfish)-predators that have the ability to force its stomach out of its mouth when they prey is too big Brittle stars-have long flexible joints that are used for capturing food. Slither along the ocean floor. Sea urchins-have no arms but tube feet extend out between sections of spines Sea Cucumbers-use their teeth to crawl along the ocean floor. Filter feeds.