''Tripneustes depressus'', the white sea urchin or sea egg, is a

species 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 s ...

sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...

in the family

Toxopneustidae Toxopneustidae is a family of globular sea urchins in the class Echinoidea. Characteristics All Camarodonts have imperforate tubercles and compound ambulacral plates. In addition, the Toxopneustids are characterised by the peristome, or opening ...

. It is found on the seabed in the tropical eastern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

including Mexico, Panama, Ecuador and the

Galápagos Islands The Galápagos Islands (Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuador ...

Description

''Tripneustes depressus'' is the largest sea urchin species in the

with a mean diameter of . The growth rate averages per month. There is very little difference in morphology between ''T. depressus'', ''

Tripneustes gratilla ''Tripneustes gratilla'', the collector urchin, is a species of sea urchin. Collector urchins are found at depths of in the waters of the Indo-Pacific, Hawaii, the Red Sea, and The Bahamas. They can reach in size. Description Collector urchin ...

'' and ''

Tripneustes ventricosus ''Tripneustes ventricosus'', commonly called the West Indian sea egg or white sea urchin, is a species of sea urchin. It is common in the Caribbean Sea, the Bahamas and Florida and may be found at depths of less than . Description The test of th ...

''; they are suspected of being the same species and genetic analysis strengthens this argument. ''T. ventricosus'' is found in the Caribbean and may have been separated from ''T. depressus'' by the closing of the land bridge between North and South America. ''T. gratilla'' has a wide range in the tropical Indo-Pacific, from East Africa to Hawaii.

Distribution

''Tripneustes depressus'' is found in the tropical eastern Pacific Ocean, occurring in Mexico, on the western coast of Central America, in Panama, in Ecuador and around the Galápagos Islands. It is found intertidally and subtidally. There is a great variation in its abundance around the Galápagos, and overall it seems to be ten times as common in 2012 as it was four decades earlier.

Ecology

The diet of ''T. depressus'' consists largely of algae and possibly also fragments of seagrass. Red filamentous algae is the main dietary constituent but pieces of

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

and other

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s have been found among its stomach contents. It may in fact be a generalist feeder rather than a herbivore, as in time of food scarcity, it sometimes turns cannibalistic.

Research

It has been shown that the coelomic fluid in the body cavity of ''T. depressus'' contains

peptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A ...

s that act as

antiviral Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do no ...

s against the

pseudorabies virus Aujeszky's disease, usually called pseudorabies in the United States, is a viral disease in swine that has been endemic in most parts of the world. It is caused by ''Suid herpesvirus 1'' (SuHV-1). Aujeszky's disease is considered to be the mos ...

(SuHV1) and the

rabies virus Rabies virus, scientific name ''Rabies lyssavirus'', is a neurotropic virus that causes rabies in humans and animals. Rabies transmission can occur through the saliva of animals and less commonly through contact with human saliva. ''Rabies lyss ...

(RV), despite the fact that neither of these viruses affect sea urchins; molecules from this species may be the basis for new drugs in the future.

References

External links

* {{Taxonbar, from=Q2515429 Toxopneustidae Animals described in 1863 Fauna of the Pacific Ocean Taxa named by Alexander Agassiz