Phylum Echinodermata

Includes starfish, sea urchins, sea cucumber & sand dollars “Spiny-skinned” Pentaradial Symmetry Coelom, no segmentation endoskeleton Lack a centralized brain- have a Nerve ring with radial and lateral nerves -sense touch, light, temp, water conditions Ouch!

Phylum Echinodermata: Anatomy Bipinnaria larvae(bilaterally symm.) Water Vascular System: -- Series of water-filled canals -- Carries out functions including respiratory, circulation, and movement. -- Oxygen, food, & wastes are carried by the water vascular system.

Phylum Echinodermata: Anatomy Water enters madreporite and flows through the stone canal and then enters the circular ring canal.madreporite Water then is separated into five radial canals that branch into double rows of bulblike structures called ampullae, which are on each side of the ambulacral ridge.ampullae The ampullae are connected to suckerlike podia = tube foottube foot

Water Vascular System

Phylum Echinodermata: Anatomy Have 5 sections or rays or arms Tube Feet: -- Act like suction cups -- Extend from the body -- Used to “walk”, capture, and hold prey *How a single tube foot moves*

Tube Feet

Class Asteroidea Star Fish

Starfish: External Anatomy Typically have 5 arms- rays thick and short Arms emerge from a central disc ossicles Have an endoskeleton of small calcareous plates called ossicles

Starfish: External Anatomy From the ossicles project spines & tubercles that are responsible for their spiny surface

Starfish: External Anatomy On the oral surface Ambulacralgrooves -- Ambulacral (am-bu-la ‘kral) grooves : Radiate out along the arms from the centrally located mouth -- Tube feet project from the grooves Ambulacral Groove

Starfish: External Anatomy On the oral surface radial nerve -- A large radial nerve can be seen in the center of each ambulacral groove between the rows of tube feet. radial canal -- Under the radial nerve is an extension of the coelom and the radial canal of the water-vascular system

Phylum Echinodermata: Anatomy They have two stomachs. One stomach is used for digestion, and the other stomach can be extended outward to engulf and digest prey.

1 - Ambulacral ossicles and ampullae. 2 - Madreporite. 3 - Stone canal. 4 - Pyloric caecae. 5 - Rectal glands. 6 - Gonads.

Phylum Echinodermata: Anatomy Starfish push their stomach out once prey is caught. -- Stomach pushes out of mouth to surround prey (ex: clam) -- Pours out enzymes -- Digests clam in its own shell -- Then it pulls its stomach and the partially digested prey into its mouth.

Groups of Echinoderms Sea Stars or Starfish -- Preys on bivalves -- Regenerates arms -- If pulled apart into pieces, each piece will grow into a new animal, as long as it contains a portion of the central part of the body.

Reproduction Starfish are capable of both sexual and asexual reproduction. Individual starfish are male or female. Fertilization takes place externally, both male and female releasing their gametes into the environment.gametes Resulting fertilized embryos form part of the zooplankton. zooplankton

Reproduction deuterostomes The fertilized embryos that float as zooplankton are known as deuterostomes. The deuterostomes then become a larva that are bilateral symmetrical. As they grow, they then change to radial symmetrical adults.

Class Echinoidea Sea Urchins & Sand Dollars

Sea Urchin -- Eat algae -- Have calcium carbonate plates covered with spines. -- Can swivel spines -- Many animals prey on sea urchins -- Yes, people eat sea urchins Call it “roe” Class Echinoidea

Sea Urchins Sea urchins are one of the sea otters favorite food. Sea otters keep sea urchin populations in check. Without sea otters, the sea urchins can devastate kelp forests which upsets the ecosystem.

Sea Urchins On the oral surface of the sea urchin is a centrally located mouth made up of five united calcium carbonate teeth or jaws, with a fleshy tongue-like structure within.calcium carbonate lantern The entire chewing organ is known as Aristotle's lantern.Aristotle

Sea Urchins test Shell, which is also called the "test", is globular in shape and covered with spines.

Sea Urchin The spines, which in some species are long and sharp, serve to protect the urchin from predators and aid in locomotion.spinespredators The spines can inflict a painful wound on a human who steps on one, but they are not seriously dangerous, and it is not clear that the spines are truly venomous

Sand Dollars

Class Echinoidea Sand Dollars -- Flattened disk -- Few animals eat/bother sand dollars. -- Burrows into the sand. -- Also called sea biscuits.

Class Holothuroidea Sea Cucumbers

Class Holothuroidea Sea Cucumbers: -- Look like warty moving pickles - - arms or rays absent - - tentacles around mouth -- Benthic: Live on the ocean floor

Sea Cucumbers Are little bull dozers -- Eat detritus in sand -- Suck up organic matter & remains of other organisms. -- Sea cucumbers extract oxygen from water in a pair of 'respiratory trees' that branch off the cloaca just inside the anus, so that they 'breathe' by drawing water in through the anus and then expelling it.

Sea Cucumber

Sea Cucumbers Mutualistic A variety of fish, most commonly pearl fish, have evolved a Mutualistic symbiotic relationship with sea cucumbers in which the pearl fish will live in sea cucumber's cloaca (anus) using it for protection from predation, The pearl fish’s waste provides a source of food/nutrients to the sea cucumber

Class Holothuroidea More Sea Cucumber -- When threatened, they spill their guts! -- It takes 1 ½ to 5 weeks to re-grow their guts -- The predator will eat the ejected guts, & leaves the sea cucumber alone. It eventually grows back the lost organs. -- Yes, people eat them!

The End