Unlocking the Potential: Deep dive into ocean of Ceramic Magnets.pptx
Phylum Echinodermata
1. • GENERAL CHARACTERS OF
PHYLUM
•CLASSIFICATION UPTO CLASSES
WITH SUITABLE EAXMPLES.
2. Echinoderms are one of the most beautiful and
most familiar sea creatures.
Sea star Star fish has become a symbol of sea life.
There are 7000 species known in echinodermata
3. History :-
Echinoderms are known since very ancient times.
Name of this phylum was introduced by Klein in
1734 .
For many years echinoderms and coelenterates
were included as a class among Radiata, because
of the radial symmetry of the adults.
Echinodermata first recognized as a group distinct
from the Radiata by Leukart in 1847.
4. What's in the name ?
Echinodermata literally means “spiny or prickly
skinned” ( Gr ., echinos, hedgehog; derma, skin)
and refers to the conspicuous spines they
possessed by their skin.
This Purple sea urchin from California has hundreds of
pointy spines for protection.
A starfish showing spines.
5. General characteristics
The phylum constitutes only major groups of
deuterostome invertebrates . Bather stated the
phylum as “ one of the best characterized and
most distinct phyla of the animal kingdom”.
They are exclusively marine i.e., they are free-
living forms (on the sea shore) and sedentary
(bottom of the sea).
6. Organ-system grade of body organization.
Triploblastic, coelomate and radially symmetrical;
often pentamerous.
Body is unsegmented with globular,
star-like, spherical,
discoidal or elongated shape.
Picture showing pentamerous symmetry
7. Cepalisation is absent, i.e., head is not present.
Endoskeleton of dermal calcareous ossicles with
spines , covered by the epidermis.
→Spines are outward projection of calcareous ossicles
diverted from the mesoderm during cleavage of egg.
They are also called as pedicelleria or tuber cells ,
which helps in the removal of body waste from the
body surface.
Body is differentiated into Oral and Aboral surfaces.
They are Euceolomate , coelome if filled with
coelomic fluid called coelomocytes. It helps in the
digestion of food particles.
8. Internally they have Water Vascular System /
Ambulacral system.
The water vascular system(WVS) of coelomic origin,
including podia or tube feet for locomotion an
usually with a madreporite.
→Madreporite are sieve like sub-circular plates with
minute pores present of Aboral surface, helps in
entry on water into the coelome of the body
Tube feet of echinoderms madreporite
9. Alimentary canal is straight or coiled .
Respiratory organs include dermal branchiae, tube
feet, respiratory tree and bursae.
Nervous system is without a brain and with a
circumoral ring around the mouth and radial nerves.
Sense organs are poorly developed include tactile
organs, chemoreceptors , terminal tentacles,
photoreceptors and statocysts.
Excretory system is absent without any excretory
organs.
10. Sexes are separate.
They are usually dioecious
Gonads are large and single or multiple.
Fertilization is external.
Development is indirect, through free-swimming
larval forms.
They exhibit great power of regeneration.