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PHYLUM ECHINODERMATA. Characteristics: Endoskeleton Calcareous (calcium carbonate) Ossicles arise from mesodermal tissue Pentaradial symmetry as adults.

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Presentation on theme: "PHYLUM ECHINODERMATA. Characteristics: Endoskeleton Calcareous (calcium carbonate) Ossicles arise from mesodermal tissue Pentaradial symmetry as adults."— Presentation transcript:

1 PHYLUM ECHINODERMATA

2 Characteristics: Endoskeleton Calcareous (calcium carbonate) Ossicles arise from mesodermal tissue Pentaradial symmetry as adults 5 sections branch off from disk Bilateral symmetry as larvae PHYLUM ECHINODERMATA

3 Characteristics Water-vascular system Helps with locomotion, attachment, and feeding Water-filled canals with extensions called tube feet Includes a ring canal that surrounds the mouth Complete digestive tract Nervous system Nerve net Nerve ring Radial nerves PHYLUM ECHINODERMATA

4 History Share an ancestor with hemichordates and chordates Evolved from bilaterally symmetrical ancestors PHYLUM ECHINODERMATA

5 Echinoderm Anatomy Tube Feet- extensions of the canal system Inside- bulblike ampulla Contracts & forces water into the tube from the water-filled canals The tube feet then extend Suction cup at the distal end Used for locomotion and/or feeding PHYLUM ECHINODERMATA

6 Echinoderm Anatomy Water-Vascular System Water enters mouth (surrounded by the ring canal) Ring canal opens to the body through a stone canal (with an opening called a madreporite) Polian vesicles- sacs connected to the ring canal Function in fluid storage Canals branch from the ring canal to transport water to the ampulla (internal portion of the tube feet) PHYLUM ECHINODERMATA

7 Echinoderm Anatomy Hemal system- strands of tissue that encircle the ring canal Circulates fluid using cilia More than likely helps to distribute nutrients (definite function is unknown) PHYLUM ECHINODERMATA

8 Sea stars 1,500 species Live on hard substances, in sand, or in mud Brightly colored Red, orange, blue, or gray 5 arms- radiate from central disk Pedicellariae Pincherlike Clean the body surface of debris Also function in protection CLASS ASTEROIDEA Pedicellariae

9 Maintenance: Diet- snails, bivalves, crustaceans, & corals Stomach- fills most of the coelom in the central disk 2 regions Larger, oral stomach (cardiac stomach)- receives ingested food Smaller, aboral stomach (pyloric stomach)- connects to pyloric cecae (absorb the food) CLASS ASTEROIDEA

10 Maintenance Feeding Force bivalves apart with the tube feet Clam vs. Sea Star The sea star inserts the cardiac stomach into the bivalve shell Gas exchange Diffusion across tissue Nervous system Nerve ring (encircles the mouth) Radial nerves extend into the arms (control the tube feet) Respond to light (photoreceptors in the arms) & chemicals CLASS ASTEROIDEA

11 Reproduction & Regeneration Can regenerate any part of a broken arm Must at least have a portion of the central disk remaining Process takes up to a year to complete Most species are dioecious 2 gonads in each arm Reproduce externally When one sea star releases gametes, pheromones stimulate other sea stars to release gametes CLASS ASTEROIDEA

12 Basket stars, brittle stars, & serpent stars > 2,000 species Long arms that give central disk a pentagonal shape Lack suction disks & ampullas Move like a snake CLASS OPHIUROIDEA

13 Sea urchins, sand dollars, & heart urchins 1,000 species Sea urchins- live on hard substrates Sand dollars & heart urchins- live in the sand or mud Move using spines & tube feet Feed on algae, bryozoans, coral polyps, & dead animal remains Aristotles lantern Chewing apparatus that cuts food into smaller pieces CLASS ECHINOIDEA

14 Sea cucumbers 1,500 species Lack arms- crawl around Lack spines Tube feet near the mouth act as tentacles Covered in mucus to trap food Produce toxins to discourage predators CLASS HOLOTHUROIDEA

15 Sea lilies & feather stars 630 species Sea lilies Attach permanently to a substrate with a stalk Crown- unattached end Feather stars Swim & crawl Lack nerve ring CLASS CRINOIDEA


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