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Echinoderms: Definition, Characteristics, and Classification and Its Role in Complete There are 0 replies:
Echinoderms: Definition, Characteristics, and Classification and Its Role in Complete Original post: Sun 11/24/2019 at 11:38 AM

Echinoderms: Definition, Characteristics, and Classification and Its Role in Complete - Do you know what Echinoderms are?? If you don't know it, you are absolutely right to visit Because on this occasion here will review about the definition of Echinoderms, Echinoderms, characteristics of Echinoderms, and the complete role of Echinoderms. Therefore, let us consider the review below.



Definition of Echinoderms

Echinoderms are derived from the Greek word Echinos, which means thorn, derma, which means skin, meaning animals with thorny skin . This group of animals includes the Star of the Sea, Star of the Snake, Sea Urchin, Sea Lilia, and Sea Cucumber. According to Kastawi et al. (2003: 267) Echinoderms are marine animals that live on the coast, but most are based on the sea.

Echinoderms are marine animals which include coelomate animals with radial symmetry, where the body can be divided into five parts arranged around a central axis. There is a large coelom of ciliated enterocoelous forming a perivisceral chamber and several convoluted systems (Marshall, 1972: 125).

Echinoderms do not have parasitic members. Echinoderms have a great ability to regenerate. Echinoderms are very widespread and this phylum consists of 5,300 species and a large number of fossils (Kastawi et al. 2005: 267).


  • Echinodermic body consists of 3 layers and has a body cavity or called tripoblastic
  • Having a symmetrical body shape bilaterally while still larvae, and as an adult radial symmetrical body shape
  • Having body skin consisting of chitin
  • Moving with the ambulacral tube legs with small holes whose function is to suck.
  • Has a perfect digestive system except for starfish that do not have the anus.
  • Does not have an excretion system
  • Sexual reproduction
  • On the surface of the body consists of protuberances that resemble thorns
  • Has a hydraulic network tube system

Echinoderms Organ System

  • Circulatory system , Echinoderms have a circulatory system that is still not. When described simply, the blood vessels start around the mouth. After that, it branches at each leg of the tube.
  • The respiratory system , Echinoderms are done by using gills or pupules (bulges in the body cavity).
  • Nervous system , Echinoderms consist of a circular nerve (ring) that supplies the mouth, and a radial nerve that resembles a cord that supplies the arms or legs of the tube.
  • The digestive system , in the form of the mouth, esophagus, stomach, intestine, and anus. It can be said, the digestive system is perfect. But there is no excretion system in Echinoderms.

Echinodermata reproduction

Echinoderms sexually reproduce, namely male and female animals that release their gamete cells into sea water, and the fertilization process that takes place externally (in seawater).

How to Live Echinoderms

Echinoderms are animals that live freely, which means that their habitat can be anywhere, from the sea to the deep sea. Food depends on the type. Examples of foods are plankton, or organisms that die or rot.


Based on body shape, Echinoderms are grouped into five classes, namely as follows:

1. Archoidea class

Echinoidea class

Echinoidea characteristics

  1. Spherical bodies, such as bowls, ovals or heart shapes, are covered by endoskeleton shells from the outer calcareal plates, divided into 5 ambulacral regions alternating with 5 inter-ambulacral regions.
  2. Podia or tube legs come out of holes in the ambulacral plates and function for movement.
  3. The mouth is located at the center of the oral surface surrounded by a membrane peristomium.
  4. The anus is located at the aboral pole and is surrounded by a membrane periproct.
  5. Ambulacral contours are absent.
  6. Pedicellaria is stemmed and has 3 pins.
  7. Echinoidea usually live in coastal areas, on rocks, seabed, in mud, wells, coastal areas, and river mouths.
  8. Sex separately, pentamerous genital glands.
  9. Breeding includes echino-pluteus larvae that swim freely.

Echinoidea Physiology

  1. Digestive system

The mouth is located at the center of the oral surface surrounded by a membrane peristomium. The anus is located at the aboral pole and is surrounded by a membrane periproct.

  1. Circulation System

No circulatory system was found

  1. Excretion system

No excretion system was found

  1. Coordination System

The nervous system is still simple

  1. Reproduction system

The reproductive system is still simple. Gonad attached to the side of the body cavity. Sperm and eggs are released directly into the water which then fertilization occurs outside the body with the meeting of the egg (ovum) and male sex cells (sperm).

2. Holothuroidea Class

Holothuroidea class

The characteristics of Holothuroidea

  • Her body is symmetrical bilaterally
  • Usually elongated or with the mouth located at one end and the anus is at the other end.
  • Body surface is rough, no spines or thorns.
  • The reduced endoskeleton is in the form of microscopic spicules or plates embedded in the body wall.
  • The mouth is surrounded by a collection of tentacles.
  • Podia or tube legs usually exist and function for movement

Holothuroidea Physiology

  1. Digestive system

The digestive tract of food is long and tortuous and cloacal usually with a tree of respiration. The digestive tract is elliptical with the position extending above the body cavity in the selom. Short esophagus is the connection from the mouth to the stomach. From the stomach the next digestive tract is a long intestine and is associated with the cloaca. The digestive tract ends with an anus in the posterior region.

Holothuroidea Physiology

  1. Circulation System
  2. Excretion system

The respiratory system is called the tree of respiration because it consists of two main channels that are branched out in two.

  1. Coordination System
  2. Reproduction system

The sexes are usually separate and the sex glands are single tubular bundles or pairs. Holothuroidea is a simple dioseus reproductive channel. Fertilization takes place externally. Zygotes develop into bilateral symmetrical ciliated larvae. This animal can also regenerate.

Order on Holothuroidea

The Aspidochirota Order

  • Have a podia or tube legs.
  • The mouth is surrounded by 10-30 tentacles, mostly 20 branching mouth tentacles.
  • The retractor muscles of the pharynx are absent.
  • There is a pair of well-developed respiration trees.

Example: Stichopus, Mesothuria, Holothuria.

Elasipoda Order

  • Have lots of podia or tube legs.
  • The mouth is in the ventral and is surrounded by 10-20 branching tentacles.
  • Example: Deima, Benthodytes.

The Order of Dendrochirota

  • Having a lot of tube legs or podia.
  • The oral dendritic or branched tentacles are like tree branches.
  • There is an oral retractor.
  • Having a tree of respiration.
  • Example: Thyone, Phyllophorus, Cucumaria.

Molpadonia Order

  • Do not have podia or tube legs, except as anal papilla.
  • Finger-shaped oral tentacles.
  • Do not have a retractor
  • Having a tree of respiration.
  • The posterior region is usually oval to the caudal area.
  • Example: Molpadia, Paracaudina.

Ordo Apoda

  • Worm-shaped body and has a smooth or warty surface.
  • Podia or tube legs are absent.
  • Oral tentacles 10-20 pieces, simple, digtate or pinnate type
  • Has a pharyngeal retractor
  • Do not have respirase trees
  • In the system of reduced water vessels.
  • Example: Synapta, Chiridota.

3. Asteria Class


Starfish ( Asteropecten irregularis ) belong to Echinoderms. Starfish usually live on the beach and in the sea to a depth of about 366 m. Some live freely, only slow movements tend to be Bentos in character except Crinoidea Group Asteroidea (Star of the Sea) there are no parasites.

There are about 5,300 types of Echinoderms that are well known to humans. The amount is very much, because these animal enemies are only a few. Starfish as Echinoderms can also be detrimental, because these sea animals as oysters / pearl oysters are also among the types of starfish that eat coral animals so that many die.

Asteria class

Asteria's characteristics

  • Star-shaped body, consisting of one central disc and five radii.
  • Having oral plains and aboral plains
  • Skeleton consists of lamina (ossikula) which are tightly arranged.
  • Lamina is located between 2 layers of binding tissue in the body wall.
  • Between the ossicles there are muscle fibers, and pores called dermal pores.
  • In the aboral part, in the ossic spine-based, there is a spina that can be moved.

Asteria Physiology

  1. Digestive system

The digestive system of the mouth food - the esophagus - to the branches of the arm - the pyloric sac - the anus.

Asteria Physiology

  1. Circulation System

Respiratory system: use a branchia dermalis / papilla in the form of a thin bag on each arm skin in the form of a bulge

  1. Excretion system

The excretion system is also secreted through the Branchia dermalis / Papulla

  1. Coordination System

The nervous system consists of a nerve ring in the mouth branching into each arm

  1. Reproduction system

Mating Reproductive System, Dioceus External fertilization of the ovum comes out about 2.5 million every 2 hours to meet sperm in water.

Sea Star Body Structure

Sea Star Body Structure

  • Madreporit: is the hole where water enters from outside the body is located on the aboral side, this is different from Ophiuroidea which is on the oral side
  • Stone channel: connecting channel between madreporite and ring gap.
  • Ring channel: a circular channel that can access all arms
  • Radial duct: channel originating from the ring channel extends to the entire arm, this channel from the ring channel is scattered to the respective tentacles
  • Lateral channel: a channel originating from a radial channel that drains water into the ampulla
  • Ampulae: a container that resembles an elastic balloon, when filled with water will form a bulge like a tube-like foot called a tube foot
  • Tube legs: feet formed by water pressure in the ampulla so that the foot can be stepped onto an object so that it can move its body
  • This ambulacral system functions to move, breathe or open prey.

How to move the Starfish

In this animal sea water enters through the dorsal plate with small holes (madreporit) leading to stone vessels. Then proceed to the ring channel that has branches to the five hands or radial channels called next to the lateral channel. In each branch there is a row of tube feet and paired with a kind of muscular bubbles or also called ampules. From the lateral channel, water enters into the ampulla.


This channel ends at the ampulla. If the ampulla contracts, then the water is compressed and enters the tube leg. As a result the tube leg turns protruding long. If this animal will move to the right, then the right tube leg will hold the object underneath and the other foot will be free. and the water will move in the opposite direction. The right tube leg holding the object will drag the animal's body towards it. That's how this animal moves. In addition, this animal also moves in water using the movements of its arms.

4. Crinoidea class

Crinoidea class

Crinoidea comes from the word Crinon which means lily and eidas which means form. This animal resembles a plant, because its shape resembles a lily, where it lives from the area below the tides to the deep sea above 12,000 feet. The most commonly studied animal is Antedon tenella. Its skin is composed of chitin. Usually attached to the bottom of the waters. If the environment is not possible, for example food runs out or safety is threatened, he will move to another place that is suitable and safe.

This group of animals is also often called a feather star. Also known as sea lilies or sea lilies are animals that have branched arms and anus and mouth are on the oral surface, the tube legs do not have suction channels and ambulatory paths are open, do not have madreporites, thorns or pedicillariae

Growing at the base with the help of an aboral surface, its small body is like a bowl called a calyx attached to the seabed with the help of roots (cirri). From the calyx, 5 flexible arms will appear, which have short tentacle parts, each with a lot of pinnulae so that it looks like a decomposed bird's feathers.

Some types of sea lilies have stalks or stems that come from the aboral area of ​​Calyx. This tool (stem) as a tool attached to the seabed, as if as a stem with roots. Most of them live in the deep sea, some are in the form of deep sea animals and some live in shallow seas, including on coral reefs.

Coral reefs

Crinoidea characteristics

  • The body shape is like a plant but some are stemmed and some are not stemmed.
  • Crinoide stemmed is an individual who can not move and his mouth directed upwards.
  • Crinoide that is not a stem is an individual who can move freely in the sea.
  • Its body resembles a lily or a lily and is shaped like a bird's feather.
  • Don't have thorns
  • The tube legs lack suber (suction device)
  • Ring-shaped nervous system which subsequently branched on each arm
  • The skin is composed of chitin. Examples of species from Crinoidea are Antedon sp, Anemon sp, Holopus, and Metacrinus (sea lilia).
  • Its size is no more than 40 cm in length and striking color.
  • Its body consists of a central disc with five arms starting from this disc each arm branching two or more.
  • Each branch has cross branches called pinul (pinnulae). These branches make animals feather.
  • The central disk is shaped like a bowl with the mouth at the bottom (below).

Crinoide Physiology

  1. Digestive system

Food in the form of small plankton or microscopic detritus, which is carried by the arm or captured by the tentacles, is passed along the ambulacral groove with wiggling feathers, which are then herded by cilia into the mouth. Having a stem that grows from discs is often used to attach animals to the base substrate, as a result the mouth stays on top and arms such as feathers create a net-like tool for capturing and transporting food to the mouth.

  1. Circulation System

The circulatory system is generally reduced and difficult to observe. It consists of blood vessels that surround the mouth and are connected by five radial vessels to each part of the arm.

  1. Excretion system

Breathing using the skin of the lungs, tube legs . The rest of the metabolism will be transported by amoeboid cells to the dermal branchiae and then released outside the body

  1. Coordination System

The nervous system consists of nerve rings and radical nerves (leading to parts of the arm).

  1. Reproduction system

Gender separated. Gonad is usually found in a pinnula. Some classes of Crinoidea release eggs in water, but some hold the pinnula until they hatch. The larvae are called doliolaria. Very young larvae still get food from egg yolks, but do not have a mouth. After a few days of being able to live freely and sticking to the end of the anterior part and then in the shape of a cup, then the arms grow. Some Crinoidea store their eggs in the body.

Order on Crinoidea

Order of Phanerozonia

  • The arms are equipped with two striking rows of marginal plates.
  • The oral plate is inframarginal and the aboral plate is supramarginal
  • Pedikelaria type bubble or sessile.
  • Podia or tube legs arranged in two rows
  • The oral skeleton is well developed and ad-ambulacral type
  • Example: Luidia, Astropecten, Archaster, and Pentaceros .

The Order of Spinulosa

  • The arms are generally without plates
  • An aboral skeleton is imbricated / reticulated with a single thorn / thorn group.
  • Pedikelaria is rare
  • Podia are contained in two lines equipped with suckers
  • Ad-ambulacral type oral skeleton
  • Single / two-pronged ampules
  • Example: Aesterina, Echinaster, Hymenaster, Solaster

Forcipulata Order

  • Marginal plates are not conspicuous
  • Aboral skeletons are mostly reticulated with conspicuous spines
  • Pediclearia type pedunculata with a basal keeping
  • Podia are arranged in four rows and are equipped with suckers
  • Example: Brisingaster, Heliaster, Zoraster , and Asterias

5. Ophiuroidea class

Ophiuroidea class

The characteristics of Ophiuroidea

  • A flat body with a pentagon or rounded central disc.
  • Oral and aboral surfaces are clear.
  • The arms are usually five, slim, smooth or thorny.
  • Do not have ambulacral curves.
  • Does not have anus and intestine.
  • Madreporit is found on the oral surface.
  • Ophiuroidea habitat is among the rocks in sea water.
  • The respiratory system uses five pairs of small air pockets located around the opening in the mouth.
  • The digestive system is in the disc ball. the reproductive system occurs outside the body by releasing male and female cells in the water, then these cells unite and will form a pluteus (ciliated larvae that will undergo metamorphosis from the shape of a sea star to the shape of a snake star).

Ophiuroidea Physiology

  1. Digestive system

Carcass eaters, animal remains, and marine animal feces. Food enters through the mouth, does not have anus. so that the rest of the food is spit out through the mouth.

  1. Circulation System

Consists of blood vessels that surround the mouth and are connected by five radial vessels to each part of the arm

  1. Excretion system

Excretion occurs in the sac called the bursae.

  1. Coordination System

Consists of a main nerve ring that works around the main disc. Do not have eyes and the like. Having the ability to feel light through receptors in the epidermis.

  1. Reproduction system

The reproductive system occurs outside the body by releasing male and female cells in the water, then these cells unite and will form a pluteus (ciliated larvae that will experience metamorphosis from the shape of a starfish to the shape of a snake star).

Order of Ophiuroidea

Ophiurae Order

  • Simple arms, mostly five.
  • Oscular arm jointed with holes and protrusions.
  • The discs and arms are usually covered by real scales or shields.
  • The spines on the arm go lateral and proceed outward or upward from the ends of the arms, not downward.
  • Single Madreporit.
  • Example: Ophioderma, Ophioscolex, Ophiolepie, and

Euryalae Order

  • Simple or branched arms, long and flexible, capable of wrapping around objects and rolling them.
  • Discs and arms without shields or underdeveloped.
  • The thorn is passed down, always forming hooks or thorns.
  • One madreporit in an inter-radius.
  • Example: Asteronyx, Astrophyton , and

The role of Echinoderms

Echinoderms are widely used by humans in various ways. The role of echinoderms is as follows:

  • The beneficial role of Echinoderms: Echinoderms are utilized by humans, including:
    1. Gonadnya sea urchins can be taken for consumption. Japan has an extensive sea urchin farm. In the territory of Indonesia, there are in East Nusa Tenggara (NTT) and Kendari.
    2. Holothuria (sea cucumber) is traded as dried sea cucumbers or sea cucumber crackers. Hong Kong is the center of the world's sea cucumber trade. In China, sea cucumbers are dried and used as medicinal ingredients.
    3. Echinoderms eat dead carcasses, so the beach becomes clean
  • The role of Echinoderms is detrimental: While the role of harm, among others:
    1. Starfish often eat pearl oysters at pearl oyster farms.
    2. Achanbasther is a pest on coral reefs, because it feeds on Coelenterata polyps.

That is a review of Echinoderms: Understanding, Characteristics, and Classification Along With Its Role in Complete  Hopefully what is discussed above is useful for readers. That is all and thank you.

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