14 Echinoderm at A- Water Vascular System & Larvae

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Phylum

Echinodermata

A presentation compiled from various sources by

Dr. PARVISH PANDYA,Zoology Dept. Bhavans College, Andheri.

Sites from which presentations have been downloaded and later editted. I am indeed thankful to them for their kindness and support :http://esg-www.mit.edu:8001/esgbio/cb/org/organelles.html http://faculty.pnc.edu/jcamp/parasit/parasit.html http://www.amnh.org/rose/hope/creatinghope/ http://www.biology.eku.edu/SCHUSTER/bio%20141/POWERPOINT %20NOTES/Intro%20to%20Protozoa_files/fullscreen.htm http://www.biosci.ohio-state.edu/~zoology/eeob405/ http://www.tulane.edu/~wiser/protozoology/pwpt/ http://www.iep.water.ca.gov/suisun/photos/wildlife.html http://www.uta.edu/biology/marshall/2343/ http://www.uta.edu/biology/faculty/faculty.html http://www.okc.cc.ok.us/biologylabs/Documents/Zoology/PowerPoint.htm http://bio.fsu.edu/ http://www.aw-bc.com/ http://www.nhm.org/ http://www.geo.cornell.edu/eas/education/course/descr/EAS302/presentations/ It is very easy to find mistakes in these presentations..I request you to kindly rectify them and supply me the modifications needed at parvishpandya@yahoo.com Thanks a lot and have fun in teaching & learning Zoology.Dr. PARVISH PANDYAs presentation

General Characteristics Adults exhibit pentamerous radial symmetry Radially symmetry is secondary; larvae are bilaterally symmetrical and undergo metamorphosis to become radially symmetrical adults.

Echinoderm larva

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General Characteristics cont.

Poorly ganglionated; possess few sensory structures Body wall contains an endoskeleton of calcareous plates - ossicles

Dr. PARVISH PANDYAs presentation

General Characteristics cont.

Possess a network of canals throughout the body - water vascular system. The canals are connected to extensions called tube feet (=podia), located on the oral surface The water vascular system is important for locomotion, feeding, and gas exchange.

Sexes are separate; gametes shed into the water; fertilization is externalDr. PARVISH PANDYAs presentation

Starfish (Asteroidea) Carnivores clams, mussels, bivalves Motile by way of tube feet endoskeleton made of calcareous plates (ie. Calcium carbonate) breathes through dermal skin gillsDr. PARVISH PANDYAs presentation

Starfish (Asteroidea) Carnivores clams, mussels, bivalves Motile by way of tube feet endoskeleton made of calcareous plates (ie. Calcium carbonate) breathes through dermal skin gillsDr. PARVISH PANDYAs presentation

Dr. PARVISH PANDYAs presentation

Starfish (Asteroidea) Carnivores clams, mussels, bivalves Motile by way of tube feet endoskeleton made of calcareous plates (ie. Calcium carbonate) breathes through dermal skin gillsDr. PARVISH PANDYAs presentation

Dr. PARVISH PANDYAs presentation

Tube Feet and Mouth

Dr. PARVISH PANDYAs presentation

Star fish The water vascular systems opening is called a madreporite. It opens into a radial canal. The radial canal then goes out to the arms in radial canals. The radial canals then feed water to the tube feet.

Dr. PARVISH PANDYAs presentation

Anus

Ring Canal

Digestive Gland in ArmDr. PARVISH PANDYAs presentation

Echinoderm Diversity

Class Asteroidea Typically have 5 arms which merge with a central disc Mouth is located in the center of oral surface which is directed downward

Dr. PARVISH PANDYAs presentation

Water Vascular System On the aboral surface is the opening of the water vascular system the madreporite (=sieve plate) Water enters the madreporite and goes through the stone canal canal to the ring canal Water then passes through a radial canal extending into each arm All along the length of these canals are lateral canals that terminate in a bulb-like structures called ampullae equipped with tube feet Tube feet line the grooves on the oral surface - ambulacral grooves

Dr. PARVISH PANDYAs presentation

How the Podia Operate Ampulla contract and force fluid into the podia causing it to become extended Suckers at the tips of the podia come into contact with the substrate and adhere to the surface Then the podia contract, thereby forcing water back into the ampulla, and the body is pulled forward

Dr. PARVISH PANDYAs presentation

Nutrition Mouth leads to a 2-part stomach: a large cardiac stomach and a smaller pyloric stomach The pyloric stomach connects with digestive glands (=pyloric cecae) that runs into each arm A short intestine extends from from the pyloric stomach to an anus on the aboral surface Associated with the intestine are rectal cecae that pump the fecal wastes out of the anusDr. PARVISH PANDYAs presentation

Soloman et al. (1999) Biology. Saunders

Dr. PARVISH PANDYAs presentation

The water vascular system has suction-cup-like tube feet used for respiration and locomotion

Anus Spines

Stomach

TUBE FEET

CANALSFigure 18.14A

Dr. PARVISH PANDYAs presentation

-Unique water-vascular system, fluid-filled tubes beginning in the madreporite and ending in blind-ending tube feet. -Tube feet used for locomotion, food gathering, and gas exchange. -Many have pedicellaria, thin, flexible stalks manipulated by muscles and with three jaws apiece that offer protection. Endoskeleton, functionally similar to arthropod exoskeleton: a hard shell encasing the body, still limits body size.

Dr. PARVISH PANDYAs presentation

Water Vascular System

Morphology:Madreporite Stone Canal Ampulla Podium Sucker1cm Asteroid water vascular system (Ruppert/Barnes)Dr. PARVISH PANDYAs presentation

Lateral Canal Radial Canal Ring Canal Tiedemanns body Polian vesicle

Additional Characteristics The endoskelton is made up of calcareous plates that often penetrate the dermis as spines Between the spines and plates are projections called papulae, which function in gas exchange and excretion Other projections on the body wall include tiny jaw-like appendages called pedicellaria

Dr. PARVISH PANDYAs presentation

Class Echinoidea Lack arms Body is enclosed in a shell or test Body surface is usually covered with moveable spines

Dr. PARVISH PANDYAs presentation

Sea Urchins Spherical body Ambulacral plates bearing tube feet that radiate out toward the aboral surface Use podia and spines during locomotion The spines are moveable and articulate with the with the calcareous ossicles

Dr. PARVISH PANDYAs presentation

Sea urchins generally feed by scraping algae off of rocks Accomplished via a complex chewing apparatus called Aristotle's lantern

Dr. PARVISH PANDYAs presentation

Class Holothuroidea Lack arms Oral-aboral axis is greatly extended Endoskeleton is reduced to a few ossicles scattered over the surface of the animal making them rather soft bodied Some species crawl along the substrate using podia; others have peristaltic locomotion via muscle contractions

Dermal ossicles

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At the oral end of the body are a group of tentacles (modified podia) that surround the mouth; used in feeding Have a muscular cloaca that is partly used in gas exchange The actual gas exchange structures are branching structures called respiratory trees

Dr. PARVISH PANDYAs presentation

Class Crinoidea Most primitive of the echinoderms Unusual in that the oral surface is directed upward Aboral surface is attached to the substrate by means of a bendable stalk The portion of the crinoid body attached to the stalk is called the crown; bears a number of arms Along the length of the arms are branches called pinnules The arms and the pinnules have ambulacral grooves with suckerless podia (secrete mucus) The ambulacral grooves are heavily ciliated and the cilia is used to direct food to the mouth (=filter feeding)

Dr. PARVISH PANDYAs presentation

Reproduction Reproduction echinos are either Male or Female. Sperm and eggs produced in the Testes or Ovaries. Symmetry of a starfish is Radial in adults, meaning if you cut it into a Chunks or many pieces, each slice is the same. Except, in the starfish larvae, they have Bilateral symmetry, just as in advanced critters like Mr. B okay not that advanced , but you know, theyre trying, okay

Asexual Repro ask a Fisherman and s/he will tell you that tearing starfish into chunks is a great way to Increase their population. Each chunk will undergo regeneration and form new starfish. So, ripping them up is not a great way to reduce predation on Shellfish, which bring in a pretty-penny.Dr. PARVISH PANDYAs presentation

C. The Trochophore Larva 1. tufts of cilia at its ends 2. ciliated band around the middle a. aquatic - ciliated band moves food toward mouth b. terrestrial - not free-swimming; remain within egg membrane

3. In mollusks - second larva - veliger a. no segmentation

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Trochophore Larva

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Life at different physical scales

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Dr. PARVISH PANDYAs presentation

Ciliated bands used in swimming and feeding

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viscous > inertial

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Measuring swimming and water movement

sand dollar pluteus larva

Cilia are also used for collecting suspended food

Gastrulation in sea urchins

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