Echinodermi

Common Brittle Star - Ophiothrix fragilis

Common Brittle Star - Ophiothrix fragilis

Ophiothrix fragilis is a species of brittle star in the order Ophiurida. It is found around the coasts of western Europe and is known in Britain as the common brittle star. ...
Crinoidi - Crinoidea

Crinoidi - Crinoidea

I Crinoidi (Crinoidea) sono una classe di echinodermi, unica classe del subphylum Crinozoa. La classe comprende 648 specie viventi e oltre 5.000 specie fossili. Sono comunemente noti come gigli di mare o stelle marine piumate. ...
Mediterranean feather star - Antedon Mediterranea

Mediterranean feather star - Antedon Mediterranea

Mediterranean feather star (Antedon Mediterranea), Lamarck, 1816) is a crinoid of the Antedonidae family, endemic to the Mediterranean Sea. ...
Oloturia - Holothuria tubulosa

Oloturia - Holothuria tubulosa

Le Oloturie (Holothuria tubulosa) sono echinodermi appartenenti alla classe Oloturoidi. Sono molto diffuse nel Mar Mediterraneo e vivono nei fondali misti di sabbia e roccia ma anche nei fondali fangosi. ...
Oloturia Maculata Cetriolo di mare a punte scure - Holothuria sanctori

Oloturia Maculata Cetriolo di mare a punte scure - Holothuria sanctori

Holothuria sanctori (Delle Chiaje, 1823) è una specie del genere Holothuria della famiglia Holothuriidae. ...
Pencil urchin - Stylocidaris affinis

Pencil urchin - Stylocidaris affinis

Stylocidaris affinis (Philippi, 1845), commonly known as pencil curl, is an echinoderm from the Cidaridae family. Stylocidaris affinis riccio matita è un echinoderma famiglia Cidaridae ...
Purple Sea Urchin - Sphaerechinus granularis

Purple Sea Urchin - Sphaerechinus granularis

Sphaerechinus granularis is a species of sea urchin in the family Toxopneustidae, commonly known as the purple sea urchin. Its range includes the Mediterranean Sea ...
Sea Urchins - Paracentrotus lividus

Sea Urchins - Paracentrotus lividus

Sea urchins are part of the echinoderms, class Echinoids. The hedgehog (Paracentrotus lividus (Lamarck, 1816)) is a sea urchin of the Parechinidae family ...
Spiny Starfish - Marthasterias glacialis

Spiny Starfish - Marthasterias glacialis

Martasteria or Spiny Starfish, Marthasterias glacialis, is an echinoderm of the Asteriidae family common in the Mediterranean Sea. Also called a Tank star, due to the characteristic plates bristling with thorns that distinguish it from other starfish,...
Stella corona di spine - Acanthaster planci

Stella corona di spine - Acanthaster planci

La stella corona di spine (Acanthaster planci) è una stella marina appartenente alla famiglia Acanthasteridae. È provvista di spine velenifere e talvolta è responsabile di invasioni molto distruttive ai danni della barriera corallina. ...
Stella Gorgone - Astrospartus

Stella Gorgone - Astrospartus

La stella marina gorgone (Astrospartus mediterraneus Risso, 1826) è un echinoderma della famiglia delle Gorgonocephalidae. ...
Stella Marina Arancione - Hacelia attenuata

Stella Marina Arancione - Hacelia attenuata

Hacelia attenuata, conosciuta comunemente come stella arancio, è una stella marina della famiglia Ophidiasteridae. Habitat e distribuzione Reperibile su fondale duro, coralligeno, da 3 a 150 metri di profondità ...
Stella marina rossa - Echinaster sepositus

Stella marina rossa - Echinaster sepositus

La stella marina rossa (Echinaster sepositus Retzius, 1783) è un echinoderma della echinasteridae famiglia, molto comune nel Mediterraneo ...
Stella marina variabile o stella marina spinosa - Coscinasterias tenuispina

Stella marina variabile o stella marina spinosa - Coscinasterias tenuispina

La stella marina variabile o stella marina spinosa minore (Coscinasterias tenuispina), Lamark,1816 ,è un echinoderma della famiglia degli Asteriidae, comune nel Mar Mediterraneo. Ha forma irregolare con braccia in numero variabile, da 6 a 12 (di solit...
Stella Serpente - Ophidiaster ophidianus

Stella Serpente - Ophidiaster ophidianus

La Stella Serpente, Ophidiaster ophidianus, è una stella marina della famiglia Ophidiasteridae diffusa nel mar Mediterraneo. Presenta lunghe braccia cilindriche, molto flessibili, che si dipartono da un piccolo disco centrale. Può raggiungere i 35–40 cm ...
Stella Serpentina Liscia - Ofiura - Ophioderma Longicauda

Stella Serpentina Liscia - Ofiura - Ophioderma Longicauda

Ophioderma longicauda, conosciuta come stella serpentina liscia, è una specie di Echinodermata della famiglia Ophiodermatidae.  ...

Echinoderms are a phylum of marine deuterostome. The name comes from the fact that they often are covered with limestone plates. The origin of the phylum dates from the Lower Cambrian, living species are about 6,000. This phylum consists of five main types of animals: starfish, sea urchins, sea cucumbers, brittle stars and crinoids. Echinodermi stelle marine ricci crinoidi Echinoderms starfish sea urchin crinoids

stella marina rossa - echinaster sepositus - mediterranean star red - intotheblue.it
stella marina rossa – echinaster sepositus – mediterranean star red – intotheblue.it

Features

Are bilateria organisms, larvae, and adults have an apparent radial symmetry, which is secondary and partial. The embryo is in fact a bilateral symmetry and resembles that of chordates. During growth there is then a predominant development of the left side of the body at the right cost

All echinoderms exhibit an external structure to pentamer symmetry at some stage of life: some undergo further changes that restore bilateral symmetry.

The nervous system is polycentric.

Echinoderms are coelomates deuterostome closely related to chordates and hemichordates.

In them, not differentiates a head and their rounded bodies are arranged with a criterion similar to the one that is used to construct a wheel. From the body of these animals, many branch of invoice varies appendices. The sea lily looks like a strange plant. It adheres to the bottom of the sea and try the food waving her long feathery tentacles that can shut themselves up like the petals of a flower. The sea cucumber is usually placed on a side of his body he stretched and moves crawling in the same manner of a worm. Starfish have long pointed arms. The Ophiothrix, while moving crawling on the bottom, flapping his arms like snakes.

Most of the echinoderms is well protected against predators. Their body is covered with limestone plates, and although this may seem hard protective coating, in fact some animals can perform many movements. Echinoderms possess two different defense systems: the quills and the pedicels.

Riproduzione Oloturia Reproduction Sea Cucumber intotheblue.it
Riproduzione Oloturia Reproduction Sea Cucumber intotheblue.it

The sea urchin spines are so long and thin that it ends up looking like a bristling ball of needles. Just as the dust collects between the fringes of a carpet, various kinds of debris can stop between these spines. When a fragment or a small animal alights on an echinoderm, the pedicels move it. Only the sea cucumber has limestone plates scattered in the skin that covers his body soft. For catching food, sea cucumbers project out from their body of the tentacles.

Paracentrotus lividus

Echinoderms have, within the body, only one of aquifers channel system, serving them to breathe, to capture prey and for locomotion. The water, entering through a perforated plate (plate madreporic), passes through a complicated system of canals connected with small pimples ambulacrali. Each pedicel widens to form a small pouch or ampoule, while at the ends with a suction cup. As the water is forced in and out of the dick, this alternately adheres to the ground when it is swollen with water and it detaches when it contracts. Each animal has hundreds of tube feet, coming out through tiny holes dermascheletro.

When echinoderms moving on a sandy bottom, the tube feet do not work; because the suction cups can go into action, it is necessary that the animal is moving on a hard surface, such as rocky. The starfish is also need some suckers to open the shells of mollusks. Echinoderms are animals lacking eyes but equally able to discern the light signals. The ends of the pedicels ambulacrali fact also represent the seat on which the photoreceptor cells, which cooperate synergistically are arranged and work collectively as one big compound eye.

Almost all of these animals feed on small organisms on the sea floor. The sea cucumber and the dollar sand swallow large amounts of sand, of which only digest the organic matter contained therein. The digestive system of echinoderms is simple and consists of a mouth placed on the lower face of the body, while the anal opening is located on the upper face, that is, in a position diametrically opposite to the mouth. The mouth and the anus are connected by a digestive tract. Echinoderms breathe by means of all the thinned parts that protrude outside. In sea urchins the respiration takes place also by means of finger-like expansions in thin walls and said hollow gills that are located on the ventral surface where the pedicellaria are also present.

La Stella Serpentina Liscia – The Brittle Starfish – Ophiodermatidae – intotheblue.it

The nervous system is represented by a simple ring of nervous tissue, which surrounds the mouth and is divided into nerve cords. A fluid fills the cavity of the body and provides to spray the organs. Echinoderms, we can distinguish three different parts of the body; the digestive tract, the body cavity and the outer wall.

ricci di mare in riproduzione - sea urchins in reproduction - intotheblue.it
ricci di mare in riproduzione – sea urchins in reproduction – intotheblue.it

The sexes are separate and fertilization takes place in the water. The larvae of echinoderms has a bilateral symmetry and its development is very different from that of the larvae of the lower invertebrates. For this echinoderms are considered animals rather evolved and in them is already possible to establish kinship ties to the most primitive chordates.

(wikipedia)

 

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