Loxechinus albus
Encyclopedia
Loxechinus albus or Chilean sea urchin
is an echinoderm
of the family
Parechinidae
, native to the coasts of Chile
and Peru
. It is found shallowly buried in fine sand, and muddy sand, beaches at and below low tide level.
flattened dorso-ventrally and densely covered in small spines. The maximum width is 100 mm. It is usually greenish, occasionally with red ambulacres and interambulacres, but large specimens from deep waters can occasionally be white. There are 6 to 11 ambulacral plates each bearing a single short primary spine and many longer secondaries. The globiferous pedicellariae have a neck between the stem and head, large valves and several lateral teeth.
Macrocystis pyrifera
. It is more numerous in exposed locations. It is a herbivore and seems to feed on whatever species of alga grow nearby. Juveniles feed on crustose coralline algae, diatom
s and algal detritus. In the Northern Hemisphere, some urchin species have large population swings and may create "barren ground" around them. In contrast, L. albus seems to be in balance with its food supply and does not seem to be limited by the quantity of algae available nor does the kelp growth become excessive. This may be partly because it also feeds on drifting algal fragments which are always abundant in kelp beds.
The spawning
period varies along the Chilean coast. Spawning period occurs later in the year as latitude increases; at 23° S it occurs in June, at 45° S (Chiloé) it occurs in November-December. The populations inhabiting the Magellan Region ( 53° S) are an exception since their spawning period lasts from July to September.
The echinopluteus larvae form part of the zooplankton
for about thirty days, feeding on phytoplankton
. They settle in the rocky intertidal zone
and undergo metamorphosis
, living in cracks in the rocks as juveniles before migrating to the neritic zone
where they mostly feed on drift algae and fronds of kelp.
Known locally in Chile as the 'Erizo rojo' (red urchin), it is harvested commercially by fishermen and is an ingredient in Chilean cuisine. Over-exploitation, its conspicuousness and lack of official harvest control means that this urchin is relatively rare in some parts of its range. It takes 8 years to reach harvestable size.
Sea urchin
Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...
is an echinoderm
Echinoderm
Echinoderms are a phylum of marine animals. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone....
of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Parechinidae
Parechinidae
Parechinidae is a family of sea urchins in the class Echinoidea.-Characteristics:All Camarodonts have imperforate tubercles and compound ambulacral plates. In addition, the characteristics of the Parechinids include the interambulacral plates being densely covered with tubercles with many subequal...
, native to the coasts of Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
and Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
. It is found shallowly buried in fine sand, and muddy sand, beaches at and below low tide level.
Description
L. albus has a testTest (biology)
A test is a term used to refer to the shell of sea urchins, and also the shell of certain microorganisms, such as testate foraminifera and testate amoebae....
flattened dorso-ventrally and densely covered in small spines. The maximum width is 100 mm. It is usually greenish, occasionally with red ambulacres and interambulacres, but large specimens from deep waters can occasionally be white. There are 6 to 11 ambulacral plates each bearing a single short primary spine and many longer secondaries. The globiferous pedicellariae have a neck between the stem and head, large valves and several lateral teeth.
Biology
L. albus is mostly found on rocky coasts associated with the kelpKelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
Macrocystis pyrifera
Macrocystis pyrifera
Macrocystis pyrifera, commonly known as Giant kelp or Giant bladder kelp, is a species of kelp , and one of four species in the genus Macrocystis...
. It is more numerous in exposed locations. It is a herbivore and seems to feed on whatever species of alga grow nearby. Juveniles feed on crustose coralline algae, diatom
Diatom
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...
s and algal detritus. In the Northern Hemisphere, some urchin species have large population swings and may create "barren ground" around them. In contrast, L. albus seems to be in balance with its food supply and does not seem to be limited by the quantity of algae available nor does the kelp growth become excessive. This may be partly because it also feeds on drifting algal fragments which are always abundant in kelp beds.
The spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
period varies along the Chilean coast. Spawning period occurs later in the year as latitude increases; at 23° S it occurs in June, at 45° S (Chiloé) it occurs in November-December. The populations inhabiting the Magellan Region ( 53° S) are an exception since their spawning period lasts from July to September.
The echinopluteus larvae form part of the zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
for about thirty days, feeding on phytoplankton
Phytoplankton
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...
. They settle in the rocky intertidal zone
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
and undergo metamorphosis
Metamorphosis
Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation...
, living in cracks in the rocks as juveniles before migrating to the neritic zone
Neritic zone
The neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters...
where they mostly feed on drift algae and fronds of kelp.
Uses