Echinus melo

Echinus melo
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Echinoidea
Order:	Echinoida
Family:	Echinidae
Genus:	Echinus
Species:	E. melo
Binomial name
	Echinus melo; Lamarck, 1816 [1]

Last updated March 26, 2019

Echinus melo, melon sea urchin, is a species of sea urchin in the family Echinidae.

In biology, a species ( ) is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more closely they represent problematic species concepts. For example, the boundaries between closely related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, and in a ring species. Also, among organisms that reproduce only asexually, the concept of a reproductive species breaks down, and each clone is potentially a microspecies.

Sea urchins or urchins are typically spiny, globular animals, echinoderms in the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres. Their tests are round and spiny, typically from 3 to 10 cm across. Sea urchins move slowly, crawling with their tube feet, and sometimes pushing themselves with their spines. They feed primarily on algae but also eat slow-moving or sessile animals. Their predators include sea otters, starfish, wolf eels, and triggerfish.

Family is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy; it is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as being the "walnut family".

Description

This species grows up to 17 cm (7 in) in diameter. It is spherical or slightly cone-shaped, and the colour of the test is mainly pinkish, yellowish, or greenish-yellow, and banded with white and pale brown, giving it a segmented appearance. The long primary spines are few in number and olive green with pale tips. They grow in a single row on each ambulacral plate. The much shorter secondary spines are yellowish green and are densely packed in several rows.^[2]

In biology, a test is the hard shell of some spherical marine animals, notably sea urchins and microorganisms such as testate foraminiferans, radiolarians, and testate amoebae.

Ambulacral is a term typically used in the context of anatomical parts of the phylum Echinodermata or class Asteroidea and Edrioasteroidea. Echinoderms can have ambulacral parts that include ossicles, plates, spines, and suckers. For example, sea stars or "star fish" have an ambulacral groove on their oral side (underside). This ambulacral groove extends from the mouth to the end of each ray or arm. Each groove of each arm in turn has four rows of hollow tube feet that can be extended or withdrawn. Opposite the ambulacral groove is an ambulacral ridge on the aboral side of each ray, known as an ambulacrum. These have interambulacra between them.

Distribution

The melon sea urchin is found in the Mediterranean Sea and the eastern Atlantic Ocean between the Azores and the Bay of Biscay, and occasionally as far north as Ireland and Cornwall.^[1]^[2]

The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Southern Europe and Anatolia, on the south by North Africa and on the east by the Levant. Although the sea is sometimes considered a part of the Atlantic Ocean, it is usually identified as a separate body of water. Geological evidence indicates that around 5.9 million years ago, the Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years, the Messinian salinity crisis, before being refilled by the Zanclean flood about 5.3 million years ago.

The Atlantic Ocean is the second largest of the world's oceans, with an area of about 106,460,000 square kilometers. It covers approximately 20 percent of the Earth's surface and about 29 percent of its water surface area. It separates the "Old World" from the "New World".

The Azores, officially the Autonomous Region of the Azores, is one of the two autonomous regions of Portugal. It is an archipelago composed of nine volcanic islands in the North Atlantic Ocean about 1,360 km (850 mi) west of continental Portugal, about 1,643 km (1,021 mi) west of Lisbon, in continental Portugal, about 1,507 km (936 mi) northwest of Morocco, and about 1,925 km (1,196 mi) southeast of Newfoundland, Canada.

Biology

E. melo is mainly a herbivore, grazing on algae, but it also consumes small invertebrates.^[3]

A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthparts adapted to rasping or grinding. Horses and other herbivores have wide flat teeth that are adapted to grinding grass, tree bark, and other tough plant material.

Invertebrates are animals that neither possess nor develop a vertebral column, derived from the notochord. This includes all animals apart from the subphylum Vertebrata. Familiar examples of invertebrates include arthropods, mollusks, annelids, and cnidarians.

Specimens from the Muséum National d'Histoire Naturelle in Paris : the likeness with a melon is obvious.

A melon is any of various plants of the family Cucurbitaceae with sweet edible, fleshy fruit. The word "melon" can refer to either the plant or specifically to the fruit. Botanically, a melon is a kind of berry, specifically a "pepo". The word melon derives from Latin melopepo, which is the latinization of the Greek μηλοπέπων (mēlopepōn), meaning "melon", itself a compound of μῆλον (mēlon), "apple, treefruit " and πέπων (pepōn), amongst others "a kind of gourd or melon". Many different cultivars have been produced, particularly of cantaloupes.

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<i>Centrostephanus longispinus</i> species of echinoderm

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References

1 2 Echinus melo Lamarck, 1816 World Register of Marine Species. Retrieved 2011-09-12.
1 2 Echinus melo European Marine Life. Retrieved 2011-09-12.
↑ Melon sea urchin (Echinus melo) Ustica Diving Resort. Retrieved 2011-09-12.

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[WoRMS-1] 1 2 Echinus melo Lamarck, 1816 World Register of Marine Species. Retrieved 2011-09-12.

[EML-2] 1 2 Echinus melo European Marine Life. Retrieved 2011-09-12.

[3] Melon sea urchin (Echinus melo) Ustica Diving Resort. Retrieved 2011-09-12.