Phylum Echinodermata

Introduction Echinoderms are spiny skinned animals Characteristics 5 part radial symmetry Internal skeleton Water vascular system Tube feet

Introduction cont. Shared characteristics with us. Internal skeleton Certain stages of development similar to ours.

Introduction Continued Diverse living areas Starfish and sand dollars live in shallow water. Others live in coral reefs or the floor of the ocean.

Form and Function Feeding Tube feet pry open shells of bivalves Carnivores- include many species of starfish Tube feet pry open shells of bivalves Flips stomach inside out Digestive juices flow out Begin to digest prey inside the prey’s own shell,

Form and Function Continued Feeding continued Stomach comes back to normal once finished Leaves empty bivalve shell behind. They eat: clams, scallops, snails, corals and other echinoderms.

Form and Function Continued Feeding continued: Filter Feeders Sea lillies, basket stars, brittle stars Use tube feet located on flexible arms to capture plankton that float by on water currents.

Brittle Star Basket Star Sea Lilly

Form and Function cont. Feeding continued Herbivores- Sea Urchins Scrape algae from rocks using their jaw.

Sea Urchin w/ Spines Sea Urchin without Spines

Form and Function Feeding continued Detritus Feeders- Sea cucumbers Move like a bulldozer across the ocean floor. Take in sand and ocean soil. Digest organic materials then rest passes out of organism.

Different Species of Sea Cucumber

Form and Function cont. Respiration Tube Feet- Diffusion of CO2 and O2

Form and Function cont. Respiration continued Skin Gills- some species have, look like bumps.

Form and Function cont. Excretion Solid waste- feces exits through the anus (except Brittle Stars, their feces exits through the mouth) Excrete ammonia through the tube feet or gills.

Form and Function Response They do not have a head, they have a primitive nervous system. Nerve ring that surrounds the mouth, radial nerves that connect to the rest of the body. Eyespots located at the tip of each arm.

Form and Function Protection Spiny skin not very protective. Adaptations: Basket stars, feather stars, spiny sea urchins move very slow Hide under rocks Some fish will turn echinoderms over to expose their soft underside and chow down.

Form and Function Movement Tube feet are attached to plates of the exoskeleton with long skinny muscles to help them move. Sand dollars and sea urchins skeleton is fused together so spines are attached to skleton which are used to creep along.

Form and Function Movement continued Brittle stars and Feather stars have flexible joints so they can use their arms for locomotion Feather stars swim for short distances. Sea cucumbers crawl like worms because endoskeleton is very reduced.

Form and Function Reproduction Most are separate sexes, some are hermaphroditic External fertilization

Form and Function Regeneration If a starfish is pulled into pieces each piece can grow into a new animal. Used to cause problems for fishermen- would cut up when they were in their nets then wonder they were twice as many when they came back.

Echinoderm Classes Only found in marine environments- no freshwater or terrestrial. Starfish Common starfish is also known as (aka) Sea Stars 5+ arms Carnivores, prey on bivalves

Leather Sea Star, Dermasterias imbricata

Echinoderm Classes Brittle Stars Tropical seas, especially coral reefs Longer, flexible arms Shed 1 or more arms when attacked or just “run” away. Filter & detritus feeders Hide during the day, hunt at night.

Echinoderm Classes Sea Urchins & Sand Dollars Eat large amounts of algae Heart Urchins and Sand Dollars hide in burrows. Sea urchins wedge themselves in rock crevices during the day and come out at night. Sharp spines- some have poison sacks to make them painful.

Sea Urchin

Echinoderm Classes Sea Cucumber Look like bumpy moving pickles. Detritus feeders Found on ocean floor- very deep One particular sea cucumber releases a glue-like substance when they are attacked. Causes the attackers to become stuck in a huge ball of glue.

Echinoderm Classes Sea Lilies and Feather Stars Filter feeders 50 plus long feathery arms Ancient species Not common, but used to be (Found in the fossil record)

Place in the World Starfish control population of bivalves. Sea urchins control algae population. Sea urchin eggs, sea cucumbers are considered delicacies in some parts of the world. Useful research subjects.