''Holothuria edulis'', commonly known as the edible sea cucumber or the pink and black sea cucumber, 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
echinoderm
An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea ...
in the family
Holothuriidae
Holothuriidae is a family of sea cucumbers, a type of echinoderm.
Description
Members of the family Holothuriidae have thick fleshy bodies and several rows of tube feet which are used for moving around and for adhering to the surface. The body ...
. It was placed in the
subgenus
In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus.
In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
''Halodeima'' by Pearson in 1914, making its full scientific name ''Holothuria (Halodeima) edulis''.
[ It is found in shallow water in the tropical ]Indo-Pacific
The Indo-Pacific is a vast biogeographic region of Earth.
In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...
Ocean.
Description
''Holothuria edulis'' is a medium-sized sea cucumber reaching a length of about . It has a roughly cylindrical shape with rounded ends but can retract and expand its body and adopt different shapes. It is usually soft and pliable with a smooth skin but, due to the special characteristics of its connective tissue
Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...
, it can become firm and rigid. The body is lined with longitudinal rows of small tube feet
Tube feet (technically podia) are small active tubular projections on the oral face of an echinoderm, whether the arms of a starfish, or the undersides of sea urchins, sand dollars and sea cucumbers; they are more discreet though present on britt ...
which can be withdrawn into the body wall, leaving small hollows. About twenty tube feet in a ring round the mouth are modified into feeding tentacle
In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...
s. This sea cucumber is usually a dark reddish-black colour on its upper side and a pinkish-mauve colour below, but can be grey or dark brown.
Image:Edible Sea Cucumber (Holothuria edulis).jpg, Classical specimen
Image:Holothuria edulis Maldives.JPG, In Maldives
Image:Holothuria edulis brownForm ZanpaOkinawa.jpg, In Japan
Distribution and habitat
''Holothuria edulis'' is a common and widespread species in the Indo-Pacific Ocean. It lives on the seabed at depths down to . Its range extends from the Red Sea
The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; T ...
and East African coast to Sri Lanka
Sri Lanka (, ; si, ශ්රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...
, Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
, China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
, Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
, the Philippines
The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no),
* bik, Republika kan Filipinas
* ceb, Republika sa Pilipinas
* cbk, República de Filipinas
* hil, Republ ...
, northern Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
and various Pacific islands. It is found in a number of different habitats including on sandy or muddy substrates, on coral rubble and in seagrass meadow
A seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and ...
s. It can be found on inner and outer reef flats, on back reef slopes and in lagoon
A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...
s.[
]
Biology
''Holothuria edulis'' is mainly nocturnal
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite.
Nocturnal creatures generally have highly developed sens ...
and tends to hide during the day under rocks or pieces of coral. It is a detritivore
Detritivores (also known as detrivores, detritophages, detritus feeders, or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, ...
and feeds by ingesting sand and debris which has accumulated on the seabed which it picks up using its feeding tentacles. Sand is pushed into the mouth and any organic matter present, including the biofilm
A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...
round the grains, is digested as the sand passes through the gut. The indigestible matter is expelled from the anus
The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, d ...
leaving a sand ridge as the animal moves around. During its feeding activities, the sea cucumber churns up the top few centimetres of seabed and aerates the sediment.[
Locomotion in ''Holothuria edulis'' is very slow. It moves mainly by ]peristaltic action
Peristalsis ( , ) is a radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an anterograde direction. Peristalsis is progression of coordinated contraction of involuntary circular muscles, which ...
of its body wall, assisted to a limited extent by its tube feet. It can also anchor its feeding tentacles into the sand and haul itself along. If it gets overturned, it can use its feeding tentacles to help right itself.[
''Holothuria edulis'' has separate sexes and spawns at any time of year with ]gamete
A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce t ...
s being liberated into the water column
A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...
. The larvae
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.
The ...
are plankton
Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
ic. This sea cucumber can also reproduce asexually by breaking into two parts, each of which then regrows the missing organs.[
]
Human use
As food
As its name implies, ''Holothuria edulis'' is edible. It is dried and sold as "'' bêche-de-mer''" or "''trepang''" in China and Indonesia.
As aquarium animal
''Holothuria edulis'' is common in the aquarium trade for its colors and its ability to eat detritus. It needs a tank size of or more. It is easy to care for but may release a toxin when stressed, although this only happens very rarely.Sea Cucumber
''Sea Cucumber''. LiveAquaria. Accessed August 30, 2016
References
{{Taxonbar, from=Q2305882
Holothuriidae
Fauna of the Indian Ocean
Fauna of the Pacific Ocean
Animals described in 1830
Taxa named by René Lesson