ADVANCED INVERTEBRATES HAVE COMPLEX BODIES AND INTERNAL SYSTEMS

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Garey Powell
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1 ADVANCED INVERTEBRATES HAVE COMPLEX BODIES AND INTERNAL SYSTEMS Arthropoda Most successful phylum on Earth Exoskeleton chitin Striated muscle Articulation Crayfish, lobsters, shrimp, crabs Echinodermata Starfish, sea urchins, sea cucumber Water-vascular system tube feet

2 Phylum: Echinodermata Echino means spiny Dermis means skin Spiny skin They have an endoskeleton internal skeleton made of calcium carbonate Composed of ossicles bony plates under the skin. Adults lack anterior and posterior. Only have 2 sides Oral surface surface with a mouth Aboral surface surface opposite mouth

3 ECHINODERMS (PHYLUM ECHINODERMATA) Basic characteristics: Pentamerous (based on five parts) radial symmetry in adults but bilaterally symmetrical larvae Water vascular system with tube feet for locomotion and feeding Skin gills for respiration Nervous system is decentralized: brain is absent Endoskeleton Many can easily regenerate lost body parts All 7,000 species are exclusively marine More closely related to vertebrates than invertebrates

FORM AND FUNCTION Water Vascular System Fluid filled tubes Carries out essential functions in echinoderms like: respiration, circulation, and movement Takes in water through Madreporite or Sieve

4 FORM AND FUNCTION Water Vascular System Fluid filled tubes Carries out essential functions in echinoderms like: respiration, circulation, and movement Takes in water through Madreporite or Sieve plate. Connected to ring canal by the stone canal. Ampulla of Tube feet are attached to the ring canal by the Radial canals. Tube feet are structures that operates like suction cups and little legs. Madreporite Stone canal Ring canal Radial canal Ampulla of tube feet.

5 Feeding FORM AND FUNCTION Sea Urchin Five part jaw scrapes algae off rocks. Sea Lilies tube feet catch plankton. Sea Cucumber take in sand and detritus as they move. Sea Star -Open mussel or clam shell, pushes stomach out of mouth, pours enzymes and digests mollusk in shell, pulls in stomach and partially digested prey into its mouth. Respiration and Circulation Most species Diffusion through tube feet and other parts of the water vascular system with the fluid-filled coelom called coelomic circulation and respiration. Some species use skin gills to exchange gas Some can do both Water vascular system is used for circulation

6 Excretion FORM AND FUNCTION Digestive waste is released through the anus Ammonia is released through diffusion by the tube feet &/or the skin gills. Response Echinoderms do not have a well developed nervous system. Nerve ring around mouth that is connected to radial nerves. Few scattered sensory cells light, chemicals, and detect gravity. Sea stars and Sea Urchins have special pincer like structures called Pedicellaria. Used to manipulate food and for defense.

7 FORM AND FUNCTION Movement Use tube feet Mobility is determined by endoskeleton Reproduction Sperm and egg released into water External Fertilization

8 GROUPS OF ECHINODERMS Phylum: Echinodermata More than >20 extinct Classes 5 living Classes ~7000 species Only live in the oceans Living Groups: Sea Urchins and Sand Dollars-Class: Echinoidea Brittle stars-class: Ophiuroidea Sea cucumbers-class: Holothuroidea Sea stars-class: Asteroidea Sea lilies and Feather Stars-Class: Crinoidea

SEA URCHINS, SAND DOLLARS (CLASS ECHINOIDEA): Sea urchins and sand dollars

test Conspicuous, movable spines (short in sand dollars) Mouth on the bottom,

feeding structure of jaws and muscles Feed on seaweeds, detritus, and

9 SEA URCHINS, SAND DOLLARS (CLASS ECHINOIDEA): Sea urchins and sand dollars Endoskeleton forms box around internal organs-rigid plates fused into a solid test Conspicuous, movable spines (short in sand dollars) Mouth on the bottom, anus on top of body Biting mouth for grazing with Aristotle s lantern, a feeding structure of jaws and muscles Feed on seaweeds, detritus, and encrusting organisms they scrape off surfaces Move with tube feet Burrow or hide in rock crevices.

10 (bkgd)comstock Images/PictureQuest, (br) Bill Ober SEA URCHIN STRUCTURE

Central disc surrounded by thin, flexible arms Internal organs are restricted to

11 BRITTLE STARS (CLASS OPHIUROIDEA): Class: Ophiuroidea Brittle Stars Largest class of echinoderms Lose arm easily if threatened Common at coral reefs No anus Central disc surrounded by thin, flexible arms Internal organs are restricted to the central disc Tube feet without suckers used for feeding on detritus and small animals

side Skin embedded with calcareous spicules, no spines Deposit feeders, most species obtaining organic matter from detritus and filter

12 SEA CUCUMBERS (CLASS HOLOTHUROIDEA): Warty pickle that moves Still radially symmetrical even if superficially appearing to have bilateral symmetry Elongated along oral-aboral axis, with mouth and anus on opposite ends and five rows of tube feet restricted to one side Skin embedded with calcareous spicules, no spines Deposit feeders, most species obtaining organic matter from detritus and filter feed Evisceration - Will release stick thread from anus when threatened-expulsion of the internal organs when disturbed; internal organs regenerate

TYPES OF ECHINODERMS-SEA STARS (CLASS ASTEROIDEA): Have a central disc in center of body surrounded by five arms (or multiples of 5) as many as 50 arms) Move with tube feet, Mostly carnivores Can

13 TYPES OF ECHINODERMS-SEA STARS (CLASS ASTEROIDEA): Have a central disc in center of body surrounded by five arms (or multiples of 5) as many as 50 arms) Move with tube feet, Mostly carnivores Can regenerate arms If completely torn apart each part that has part of central disk grows in individual. Internal organs extend through the entire body, including the arms Calcium carbonate plates are loosely embedded in spiny skin making them slightly flexible Pedicellariae pincer-like organs that keep skin clean

14 (bkgd)comstock Images/PictureQuest SEA STAR STRUCTURE

CLASS CRINOIDEA: FEATHER STARS AND SEA LILIES Crinoids Most

water Feather stars can swimcrawl on the bottom and live

Mouth located on upper surface Tube feet secrete mucus to

18 CLASS CRINOIDEA: FEATHER STARS AND SEA LILIES Crinoids Most ancient echinoderms Sea lilies sessilelive attached in deep water Feather stars can swimcrawl on the bottom and live mostly in shallow-water coral reefs in the tropics. Mouth located on upper surface Tube feet secrete mucus to aid in food capture. Five or more arms branch out for suspension feeding

19 Ecology of Echinoderms When populations of echinoderms fluctuate it causes major changes in other organisms populations. Crown of Thorns sea star is causing major damage to the Great Barrier Reef in Australia Feeds on the coral.

Spiny skinned animals with radial symmetrical body plan. Rays emanating from a common center. Internal skeleton of hardened plates of calcium

Echinodermata Spiny skinned animals with radial symmetrical body plan. Rays emanating from a common center. Internal skeleton of hardened plates of calcium carbonate. Water vascular system and tube feet