Phylum Echinodermata Sea stars, brittle stars, sea urchins, sea cucumbers, sand dollars

The Basics Echinodermata Echinodermata means “spiny skin” About 7000 species – all marine Planktonic larvae are bilateral Adults are radially symmetrical Pentamerous – symmetry based on 5 parts They have an oral (mouth) side and an aboral side Have an endoskeleton Possess a water vascular system Tube feet usually have suckers and are used for attachment, locomotion, and receiving chemical and mechanical stimuli

The Types – Sea Stars Echinodermata Most species have 5 arms that radiate around a central disk Some species can have up to 50 arms Hundreds of tube feet cover the oral surface Can move in any direction by reaching out their tube feet and pulling themselves along Endoskeleton consists of interconnected calcium carbonate plates that form a relatively flexible framework Allows their arms to be somewhat flexible Aboral surface is often covered with spines Feed on bivalves, snails, barnacles, and any other attached or slow moving animal

Echinodermata – Sea Stars Ochre Sea Star Northern Pacific Sea Star Sun Star Echinodermata – Sea Stars Cushion Sea Star Goose Foot Sea Star Common Sea Star Spiny Sea Star Crown of Thorns Sand Star

The Types – Brittle Stars Echinodermata Have 5 arms that are long, very flexible, and sharply defined from the central disk The snake-like arms are used in locomotion The tube feet (lacking suckers) are used for feeding Most eat detritus and small animals they pick up from the bottom Largest group of echinoderms as well as the most widely distributed

Echinodermata – Brittle Stars Blunt Spined Brittle Star Banded Brittle Star Echinodermata – Brittle Stars Green Brittle Star Millipede Brittle Star Heart Brittle Star Ruby Brittle Star

The Types – Sea Urchins Echinodermata Endoskeleton forms a round, rigid, shell- like test with movable spines Locomotion is achieved by the movable spines, jointed to sockets in the test, and the sucker-tipped tube feet Graze on seaweeds and seagrasses, but will also ingest detritus Mouth has an intricate system of jaws and muscles called Aristotle’s Lantern Used to bite off algae and other bits of food from the bottom Found worldwide on rocky shores

Echinodermata – Sea Urchins Long Spined Urchin Pencil Urchin Echinodermata – Sea Urchins Black Hatpin Urchin Crown Urchin Boring Urchin Fire Urchin

The Types – Sea Urchins Echinodermata Sand dollars and heart urchins are closely related to urchins Flattened bodies with shortened spines, deposit feeders

The Types – Sea Cucumbers Echinodermata The animal lies on one side, where the 5 rows of tube feet are concentrated The oral and aboral surfaces are at the ends Endoskeleton consists of microscopic, calcareous spicules scattered through the warty, often tough, skin Deposit feeders Tube feet around the mouth are modified into tentacles that are used to scoop food into mouth Lack spines so they have other defense mechanisms: secretion of toxic substances, expulsion of internal organs

Echinodermata – Sea Cucumbers Chocolate Chip Sea Cucumber Echinodermata – Sea Cucumbers Beaded Sea Cucumber Sea Apple Sea Cucumber Pink Warty Sea Cucumber

The Types - Crinoids Echinodermata Suspension feeders that use outstretched, feathery arms to obtain food from the water Includes feather stars and sea lilies Capable of swimming Body plan is best described as an upside- down brittle star with the mouth directed upward Some only have 5 arms, while others may have up to 200 arms (because of branching of the initial 5 arms) Tiny tube feet secrete a mucus to aid in catching food particles

Echinodermata - Crinoids

Digestion and Feeding Echinodermata Sea stars are carnivorous and extend their stomach inside out through the mouth to envelop the food Sea urchins and sea cucumbers have long and coiled guts Sea urchins need the long gut in order to digest plant material Sea cucumbers need the long gut in order to process large amounts of sediments to obtain enough organic matter for survival

Sea Star with expelled stomach Echinodermata

Respiration and Circulation Echinodermata Have a water vascular system, which is a system of internal tubes filled with fluid Moves water, nutrients, gases, and wastes throughout the body Tube feet are the main surface for respiration (gas exchange)

Water Vascular System Echinodermata

Excretion Echinodermata Digestive wastes are released as feces through the anus Nitrogen-containing cellular wastes are excreted in the form of ammonia This waste is passed into surround water through the tube feet and skin

Nervous System Echinodermata Very simple Have a nerve ring that surrounds the mouth and radial nerves that connect the ring with the body parts Do not have a brain Coordinates movements of tube feet and spines Most have scattered sensory cells that detect light, gravity, and chemicals released by potential prey Many have the ability to turn their bodies over after being flipped Sea urchins have also been known to camouflage their bodies with debris

Echinodermata

Reproduction Echinodermata Most species have separate sexes Mostly external fertilization through spawning Developing larvae become part of the plankton Some sea stars, brittle stars, and sea cucumbers regularly reproduce asexually by the separation of the central disk/body into two pieces Each piece then grows into a complete individual Regeneration – the ability to regrow lost arms and damaged body parts

Echinodermata

Echinoderms: the ultimate animal Video 14 min Echinodermata http://www.shapeoflife.org/video/ech inoderms-ultimate-animal