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Echinodermata – Definition, Classification, Characteristics, Examples

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  • Last Updated : 21 Jul, 2022
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Everywhere on earth, there are a variety of living things. The earth’s warm, humid regions are home to a wide variety of species, earning them the moniker region of enormous biodiversity. And over 50% of the world’s biodiversity is found in just 12 countries. Another among them is India.

Each person has a distinct DNA configuration. Human beings differ from one another in terms of how we appear and the various factors that influence it, including our length, complexion, and so forth. If we were to contrast ourselves with another species, such as a horse or a fish, we might undoubtedly differ considerably in practically every way, but if we did so, we would only be able to identify a few differences.

Echinodermata

Star Fish

 

Echinoderm is a phylum of creatures that only includes marine life. There have been no signs like any land or water would be fresh echinoderms up to this point. These organisms are multicellular and have highly developed organ systems. The traits and traits of all the species in this phylum are the same. They are colorful creatures with distinctive forms. They are crucial both geologically and biologically. Both the intertidal zones and the seafloor are home to echinoderms. The fact that every member of  Echinodermata is a marine organism is an intriguing aspect of this phylum. Both freshwater and marine organisms are not present.

In echinoderms, a vascular system which would be water Is responsible for gaseous exchange, nutrient circulation, and waste removal.

Characteristics

  • They are round or elongated and have a star-like appearance.
  • They are only marine creatures.
  • The creatures have spiky skin.
  • Organ system-level organizations can be seen in them. Most members have a digestive system in addition to a circulatory system.
  • They have cavities Which would be calm and triploblastic.
  • The calcium carbonate makes up the skeleton.
  • Their circulatory system is open.
  • They use their gills or the cloacal respiratory tree to breathe.
  • They lack an excretory system and have a straightforward radial nerve system.
  • With no recognizable head, the body is not segmented.  Anus would be on the dorsal and the mouth would be ventral.
  • The tube feet make moving around easier.
  • Both sexual and asexual gametic fusion and regeneration are used in their sexual reproduction. External factors fertilize a crop.

Classification

Asteroidea

  • They have five arms and a flattened, star-shaped body.
  • Their feet are tube-shaped suckers.
  • Through papillae, they breathe.
  • Calcareous plates and mobile spines make up the body. Calcareous ossicles help in the protection.
  • There is pedicellaria.
  • Example: Asterias and Zoroaster

Ophiuroidea

  • The body has pentamerous discs and is flat.
  • There are no suckers on the tube feet.
  • Through the bursae, they breathe.
  • The middle disc is separated from the lengthy arms.
  • Example: Ophiderma and Amphuria

Echinoidea

  • It has a hemispherical shape.
  • Suckers are present in the tube foot.
  • There are no arms on the body.
  • The spines can move, and the organ has a little skeleton.
  • Aristotle’s Lantern is the name for the complex mouth mechanism that sea urchins have on the bottom of their bodies. This muscular framework comprises a strong set of jaws and 5 pointed structures that resemble teeth and may work in different directions.
  • Example: Echinus and Cidaris

Holothuroidea

  • The body is cylindrical and long.
  • There are no arms, spines, or pedicellariae.
  • The cloacal pulmonary branch is how they breathe.
  • They have suckers on their tube-shaped feet.
  • Example: Cucumaria and Holothuria

Crinoidea

  • It has a star-like body.
  • These would exhibit unique characteristics of shedding.
  • None of the tube feet are suckers.
  • The arms split in two.
  • Pedicellariae and spines are not present.
  • Example: Antedon, Neometra, etc.

Conceptual Questions

Question 1: What is the use of calcareous ossicles?

Answer:

These are present in the Asteroidea.Small calcareous components known as ossicles are lodged in the skin of an  body wall of echinoderms.  They would play an essential role in protection and strength as a component of the endoskeleton.

Question 2: What are the adaptations of crinoidea?

Answer:

Live comatulid  crinoidea would have capacity to autotomize and rejuvenate their viscera. Some subgroups of surviving crinoids, such as isocrinids and comatulids, have unique structural articulations that permit the shedding and regeneration of their arms and stems.

Question 3: How do echinoderms breathe?

Answer:

Echinoderms, in practice, breathe simply using diffusion, moving oxygen and water throughout their anatomy using gills or other specialised appendages resembling tube feet.

Question 4: What would echinoderms use to make up skeleton?

Answer:

The very improved performance with which echinoderms use calcium carbonate which would  allows them to use the least amount of resources while yet meeting the volume and toughness demands of a good skeleton.

Question 5: How would echinoderms use to move or grip?

Answer:

A network of water-filled channels radiating off of a canal which is ring  that surrounds the gut is the water-vascular system shared by all echinoderms. The echinoderm can walk, hold the substrate, or handle items with the help of sucker-like extensions called tube feet, which emerge from the canals.

Question 6: What is meant by Aristotle’s lantern?

Answer:

Aristotle’s Lantern is the name for the complex mouth mechanism that sea urchins have on the bottom of their body. This muscular framework comprises of a strong set of jaws and 5 pointed structures that resemble teeth and may work in different directions.

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