Types specimens of echpnodermata, Biology

Assignment Help:

Types specimens of echpnodermata

Before we begin the study of the selected specimens of the following echinoderms - Feather star, Brittle star, Sea urchin, Sea cucumber and Star fish. You should be aware that though members of the various classes of ecchinoderms often appear to be superficially different, however their structure is fundamentally similar. For example sea cucumbers tack the five arms of sea stars, but they do have five bands of tube feet and thus show the same basic pentaradiate symmetry.

Antedon is commonly called "feather star" or "sea lily" Examine the specimen and note the following features:

(i)The body of Antendon is made of a central convex disc of calyx and five equidistant, elongated slender radiating arms.

(ii)Each arm is divided into two branches at the base, so there are in effect ten long arms.

(iii)The arms are slender, flexible, movable and bear small spine-like structures or pinnules on the two sides.

(iv)The body has a distinct upper oral and lower aboral surface.

(v)Aboral surface bears several root-like, slender, curved, jointed cirri supported by small ossicles which help to attach Antedon to rocks.

(vi)Oral surface is covered with a soft and leathery skin, called tegmen and this surface bears the mouth and anus on the same side of the calyx. The anus is borne on a tiny papilla and is excentric whereas the mouth is in the center.
 
(vii)Five ambulacral ciliated grooves radiate from the mouth towards the arms. Each groove divides into two and runs along the oral surface of each arm.

(viii)The intervening body surface is the adambulacra.

(ix)Tube feet or podia are without suckers and can be seen along the edges of ambulacral groove.

(x)The exoskeleton is made of calcareous ossicles or plates.


Related Discussions:- Types specimens of echpnodermata

Specie concept, what is nomenalistic specie concept

what is nomenalistic specie concept

The right side of the container, A solute passes from higher concentration ...

A solute passes from higher concentration on the left of a container to the right side of container thru a membrane. What would happen if a second solute of lower concentration was

Pisces, examples of pisces

examples of pisces

Define national programmes targeting infants and preschooler, Explain Natio...

Explain National Programmes Targeting Infants and Preschoolers? Infants and preschoolers are the vulnerable sections of the society. To give them due  coverage, some national p

Define that dna is the genetic material, How did Alfred Hershey and Martha ...

How did Alfred Hershey and Martha chase arrive at the conclusion that DNA is the Genetic material?

What do you mean by taxonomist, Q. What do you mean by Taxonomist? Mode...

Q. What do you mean by Taxonomist? Modern classification systems are based on many types of evidence. A truly natural classification is obtained from analysis and harmonisation

Show the principle parts of a mold, Q. Show the principle parts of a mold? ...

Q. Show the principle parts of a mold? The principle parts of a mold are a web-like structure known as mycelium and the spore. The mycelium is often white and cottony and penet

Explain starch gelatinization, Starch gelatinization Undamaged starch ...

Starch gelatinization Undamaged starch granules are insoluble in cold water but can imbibe water  reversibly i.e. they can swell slightly and then return to their original siz

Treatment of hypertension, Elderly Is the treatment of hypertension di...

Elderly Is the treatment of hypertension different in elderly? Generally, the target for treatment should be at lower levels in the elderly. This is because, the elderly have

What is nervous system, What is Nervous System? The nervous system is m...

What is Nervous System? The nervous system is made up of associations of cells called neurons. Bundles of neurons are called nerves. The nervous system is divided into two part

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd