Echinocardium cordatum | |
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Belgian continental shelf specimen | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Echinodermata |
Class: | Echinoidea |
Order: | Spatangoida |
Family: | Loveniidae |
Genus: | Echinocardium |
Species: | E. cordatum |
Binomial name | |
Echinocardium cordatum | |
Synonyms | |
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Echinocardium cordatum, also known as the common heart urchin [2] or the sea potato, [3] is a sea urchin in the family Loveniidae. It is found in sub-tidal regions in temperate seas throughout the world. [4] [5] It lives buried in the sandy sea floor.
The sea potato is a heart-shaped urchin clothed in a dense mat of furrowed yellowish spines which grow from tubercles and mostly point backwards. The upper surface is flattened and there is an indentation near the front. This urchin is a fawn colour but the tests that are found on the strandline have often lost their spines and are white. During life, the spines trap air which helps prevent asphyxiation for the buried urchin. [2] The ambulacra form a broad furrow in a star shape extending down the sides of the test. There are two series each of two rows of tube feet. The test reaches from six to nine centimetres in length. [3]
The species was first described as Echinus cordatum in 1777 by Thomas Pennant. [1] [6] It has subsequently been synonymised with Echinocardium sebae Gray, 1825, [1] [7] Spatangus arcuarius Lamarck, 1816, [1] [8] Echinocardium australe Gray, 1851, [1] [9] Echinocardium stimpsonii A. Agassiz, 1864, [1] [10] Echinocardium zealandicum Gray, 1851, [1] [9] Amphidetus novaezelandiae Perrier, 1869, [1] [11] and Amphidetus kurtzii Girard, 1852. [1] [12]
The sea potato has a discontinuous cosmopolitan distribution. It is reported from temperate seas in the north Atlantic Ocean, the west Pacific Ocean, around Australia, New Zealand, South Africa and the Gulf of California at depths of down to 230 metres. [13] A 2016 study revealed that it was a complex of at least 5 species, with three in Europe, one in Australia and one in the NW Pacific. [4] It is very common round the coasts of the British Isles in the neritic zone. [14]
The sea potato buries itself in sand to a depth of ten to fifteen centimetres. It occurs in sediments with a wide range of grain sizes but prefers sediments with a size of 200 to 300 μm and a low mud content. [15] It makes a respiratory channel leading to the surface and two sanitary channels behind itself, all lined by a mucus secretion. [1] The location of burrows can be recognised by a conical depression on the surface in which detritus collects. This organic debris is used by the buried animal as food and is passed down by means of the long tube feet found in the front of the ambulacrum. [14]
The sexes are separate in the sea potato and the males and females both liberate gametes into the water table in the spring. The echinoplutei larvae that develop after fertilisation have four pairs of arms and are laterally flattened. In late stage larvae, tube feet may be seen developing round the skeleton. [16] The larvae are pelagic and form part of the zooplankton. Metamorphosis takes place about 39 days after fertilisation with the larvae settling out and burrowing into the substrate. [17] The lifespan of the sea potato is thought to be ten or more years. [18]
In the sandy sea bed that it favours, the sea potato is often found in association with the bivalve molluscs Tellina fabula , Ensis ensis and Venus striatula . [19]
The bivalve Tellimya ferruginosa is often found living inside the sea potato's burrow as a commensal. Up to fourteen have been found in one burrow with the young being attached to the spines of the urchin by byssus threads. [20] Another species that makes use of the burrow is the amphipod crustacean, Urothoe marina . [21]
The test (shell) of the sea potato has cultural significance in West Cork, Ireland, where it is traditionally referred to as a "Virgin Mary" shell. [22] According to traditional belief, the distinct patterns visible on the test are thought to resemble an apparition of the Virgin Mary. There is also a traditional association between the appearance of the shells on beaches in West Cork and the Marian month of May and the Feast of the Assumption. [23]
Sand dollars are species of flat, burrowing sea urchins belonging to the order Clypeasteroida. Some species within the order, not quite as flat, are known as sea biscuits. Sand dollars can also be called "sand cakes" or "cake urchins".
Echinarachnius parma, the common sand dollar, is a species of sand dollar native to the Northern Hemisphere.
The diadema urchin or blue-black urchin is a species of tropical sea urchin, member of the Diadematidae family.
Loveniidae is a family of heart urchins in the order Spatangoida.
Echinocardium is a genus of sea urchins of the family Loveniidae, known as heart urchins. The name is derived from the Greek ἐχῖνος and καρδία.
Echinocardium australe is a sea urchin in the family, Loveniidae, first described by John Edward Gray in 1851, from specimens collected in Port Jackson and Tasmania. It is a synonym of Echinocardium cordatum.
Meoma ventricosa, known by the common names cake urchin and red heart urchin, is a large species of sea urchin which lives in shallow waters in the Caribbean. It may reach a diameter of twenty centimeters and is covered in reddish-brown spines. It has both pentagonal radial symmetry and bilateral symmetry, giving it a sand-dollar appearance; however, two of its five sections are merged more closely than the others.
Lytechinus variegatus, commonly called the green sea urchin or the variegated sea urchin, is a species of sea urchin that can be found in the warm waters of the western Atlantic Ocean and Caribbean Sea.
Eucidaris tribuloides, the slate pencil urchin, is a species of cidaroid sea urchins that inhabits littoral regions of the Atlantic Ocean. As a member of the basal echinoid order Cidaroida, its morphological, developmental and molecular genetic characteristics make it a phylogenetically interesting species.
Dendraster excentricus, also known as the eccentric sand dollar, sea-cake, biscuit-urchin, western sand dollar, or Pacific sand dollar, is a species of sand dollar in the family Dendrasteridae. It is a flattened, burrowing sea urchin found in the north-eastern Pacific Ocean from Alaska to Baja California.
Cidaridae is a family of sea urchins in the order Cidaroida.
Toxopneustes pileolus, commonly known as the flower urchin, is a widespread and commonly encountered species of sea urchin from the Indo-West Pacific. It is considered highly dangerous, as it is capable of delivering extremely painful and medically significant stings when touched. It inhabits coral reefs, seagrass beds, and rocky or sandy environments at depths of up to 90 m (295 ft). It feeds on algae, bryozoans, and organic detritus.
Ensis ensis, or the sword razor, is a razor clam, a marine bivalve mollusc in the family Pharidae. It lives buried in the sand and is found off the coasts of northwest Europe.
Fabulina fabula, the bean-like tellin, is a species of marine bivalve mollusc in the family Tellinidae. It is found off the coasts of northwest Europe, where it lives buried in sandy sediments.
Eucidaris is a genus of cidaroid sea urchins known as slate pencil urchins. They are characterised by a moderately thick test, a usually monocyclic apical disc, perforate and non-crenulate tubercles and nearly straight ambulacra with horizontal pore pairs. The primary spines are few and widely spaced, stout with blunt flat tips and beaded ornamentation and the secondary spines are short and apressed. They originated in the Miocene and extant members of the genus are found in the tropical Indo-Pacific Ocean, East Pacific, Atlantic Ocean and Caribbean Sea.
Toxopneustes maculatus is a rare species of sea urchin found in the Indo-West Pacific.
Acrocnida brachiata, the sand burrowing brittlestar, is a species of brittle star in the family Amphiuridae. It occurs on the seabed in the northeastern Atlantic Ocean and the North Sea, living semi-buried in the sand with only its arm tips projecting.
Echinocardium flavescens, sometimes called the yellow sea potato, is a species of sea urchin in the family Loveniidae, chiefly found in the northeast Atlantic region.
Echinocardium pennatifidum is a species of sea urchin in the family Loveniidae, chiefly found in the northeast Atlantic region.