''Sterechinus neumayeri'', the Antarctic sea urchin, 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 ...
of
sea urchin in the
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Echinidae. It is found living on the seabed in the waters around Antarctica. It has been used as a
model organism in the fields of
reproductive biology
Reproductive biology includes both sexual and asexual reproduction.
Reproductive biology includes a wide number of fields:
* Reproductive systems
* Endocrinology
* Sexual development (Puberty)
* Sexual maturity
* Reproduction
* Fertility
Human ...
,
embryology
Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, ''-logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos ...
,
ecology
Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overl ...
,
physiology
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
and
toxicology
Toxicology is a scientific discipline, overlapping with biology, chemistry, pharmacology, and medicine, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating e ...
.
Molecular phylogeny
The
mitochondrial DNA of the Antarctic sea urchin and several other urchins found in the circumpolar region was examined in order to assess their
phylogenetic relationships. It was found that ''Sterechinus neumayeri'' was most closely related to ''
Paracentrotus lividus
''Paracentrotus lividus'' is a species of sea urchin in the family Parechinidae commonly known as the purple sea urchin. It is the type species of the genus and occurs in the Mediterranean Sea and eastern Atlantic Ocean.
Description
''Paracent ...
'' and ''
Loxechinus albus
''Loxechinus albus'' is an echinoderm of the family Parechinidae, native to coastal southern South America, ranging from Ecuador, along the entire coasts of Peru and Chile, to Argentina, as well as the Falkland Islands. It is the only species in ...
'', both of which are found in the southernmost part of South America. The divergence of the three species began 35 to 25 million years ago, which coincides with the period at which Antarctica became separated from South America.
[
]
Description
The Antarctic sea urchin ranges in color from bright red to dull purple and can grow to in diameter. The test is globular with vertical rows of long, strong, white-tipped spines between which there is a dense covering of smaller spines and vertical rows of tube feet. The spines and tube feet enable the animal to move across the ground. There are often fragments of red algae adhering to the spines.[Antarctic Sea Urchin Shows Amazing Energy-Efficiency in Nature's Deep Freeze 15 March 2001]
University of Delaware. Retrieved 22 March 2018
Distribution
The Antarctic sea urchin is found in circumpolar waters including the Southern Ocean
The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-small ...
, the Balleny Islands, South Georgia and the South Sandwich Islands
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, song_type =
, song =
, image_map = South Georgia and the South Sandwich Islands in United Kingdom.svg
, map_caption = Location of South Georgia and the South Sandwich Islands in the southern Atlantic Oce ...
, Terra Nova Bay
Terra Nova Bay is a bay which is often ice free, about long, lying between Cape Washington and the Drygalski Ice Tongue along the coast of Victoria Land, Antarctica. It was discovered by the British National Antarctic Expedition (known as the ...
and Victoria Land
Victoria Land is a region in eastern Antarctica which fronts the western side of the Ross Sea and the Ross Ice Shelf, extending southward from about 70°30'S to 78°00'S, and westward from the Ross Sea to the edge of the Antarctic Plateau. I ...
.[ Most of the specimens found have been in water down to a depth of about .
]
Biology
The Antarctic sea urchin largely feeds on diatoms and other algae. It also consumes foraminifer
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an ...
ans, amphipods, bryozoa
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a ...
ns, hydrozoa
Hydrozoa (hydrozoans; ) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be large, and in some cases the specialize ...
ns, polychaete worms and 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 throug ...
s and also seal
Seal may refer to any of the following:
Common uses
* Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly:
** Earless seal, or "true seal"
** Fur seal
* Seal (emblem), a device to imp ...
faeces
Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relati ...
when available.
The Antarctic sea urchin is often found living in association with the Antarctic scallop, ''Adamussium colbecki
The Antarctic scallop (''Adamussium colbecki'') is a species of bivalve mollusc in the large family of scallops, the Pectinidae. It was thought to be the only species in the genus ''Adamussium'' until an extinct Pliocene species was described ...
'' and the seastar, ''Odontaster validus
''Odontaster validus'' is a species of sea star in the family Odontasteridae. Its range includes the Southern Ocean and the seas around the mainland and islands of Antarctica.
Description
''Odontaster validus'' can grow to about 10 cm (4&n ...
''.
Research
Metabolism
Metabolic processes tend to slow down as the temperature decreases and the Antarctic sea urchin lives in an extremely cold environment. A research study has found that the larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
...
e use energy 25 times more efficiently than other organisms do.[ Mature urchins were collected from under the sea ice and moved to a research laboratory at ]McMurdo Sound
McMurdo Sound is a sound in Antarctica. It is the southernmost navigable body of water in the world, and is about from the South Pole.
Captain James Clark Ross discovered the sound in February 1841, and named it after Lt. Archibald McMurdo ...
where they were induced to spawn. Over 10 million embryos were used to test the protein turnover rates and the associated changes in metabolic rates in the larvae as they developed and this super-efficiency was found. Despite this, it took the larvae a year to develop into juveniles. The mechanism for this energy efficiency was unclear but it was surmised that if it could be transferred through genetic manipulation to other organisms such as clams, oysters or fish, it could transform aquaculture.[
]
Global warming
A research study examined whether the reproductive capacity of the Antarctic sea urchin and the Antarctic proboscis
A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...
worm ('' Parborlasia corrugatus'') would cope with the increased ocean acidification
Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...
that would be likely to accompany global warming
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
. It was found that a lowering of the pH from the normal level of 8.0 to 7.0 had little effect on reproduction in the worm, apart from a slight increase in the number of abnormal later-stage embryos. In the urchin, fertilisation rates were reduced at a pH below 7.3, but only at low sperm concentrations. There was a considerable increase in abnormal embryos at later stages of development under lowered pH conditions. In the case of these two cold water 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, these results were not more significant than those of other example organisms from more temperate regions of the world.
References
{{Taxonbar, from=Q1748672
Echinidae
Fauna of the Atlantic Ocean
Fauna of the Southern Ocean
Animals described in 1900