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

Define the beer''s law - nutritional biochemistry, Define the Beer's Law -...

Define the Beer's Law - Nutritional  Biochemistry? Beer's law states that the concentration of a substance is directly proportional to the amount of light absorbed or inversely

Biodiversity and economics, With the survival and well-being of humans bein...

With the survival and well-being of humans beings so heavily dependent on biodiversity, its economic value assumes considerable importance. For instance the economic value of ecosy

Poisoning - pesticide toxicity, P o i s on i n g P e sticide ...

P o i s on i n g P e sticide toxicity Chemical pesticides were introduced as an important tool for pest control and have been used extensively in human health ope

Plants of dry environment open their stomata only at night, Why do few plan...

Why do few plants adapted to a dry environment open their stomata only at night? Throughout the day in dry habitats the guard cells become the stomata close and flaccid; concur

How do bacteria reproduce, How do bacteria reproduce? Bacteria replicat...

How do bacteria reproduce? Bacteria replicate by binary fission (scissiparity). Some bacteria though present a kind of sexual reproduction (transformation, transduction or conj

Interkinesis, There is no Interphase preceding second meiotic division. ...

There is no Interphase preceding second meiotic division. There is a brief intervening period called Interkinesis During this period there may be synthesis of some reserve fo

What is the main evolutionary novelty presented by annelids, What is the ma...

What is the main evolutionary novelty presented by annelids? The main evolutionary novelty shown by the beings of the phylum Annelida is the coelom, the internal body cavity to

Role of carbohydrates in dyslipidemia, Q. Role of Carbohydrates in dyslipid...

Q. Role of Carbohydrates in dyslipidemia? It is important to know about these carbohydrates, as they all differ in their digestive properties. The rate of absorption is variabl

Difference between micronutrients and macro, Q. What is the difference betw...

Q. What is the difference between micronutrients and macro? The classification criterion of nutrients into micronutrients and macro has no relation to the size of the molecul

Sexology, what is meant by double penetration sex?

what is meant by double penetration sex?

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