Australostichopus
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''Australostichopus'' is a genus of
sea cucumbers Sea cucumbers are echinoderms from the class Holothuroidea ( ). They are benthic marine animals found on the sea floor worldwide, and the number of known holothuroid species worldwide is about 1,786, with the greatest number being in the Asi ...
in the family
Stichopodidae The Stichopodidae are a Family (biology), family of sea cucumbers, part of the order Synallactida. Description Members of this family are mostly large or medium-sized sea cucumber, holothuroids with an angular body shape (almost forming a squar ...
. It is
monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...
, being represented by the single species ''Australostichopus mollis'',Moraes,G., Norhcote, P.C., Kalinin,V.I. ,Avilov, S.A., Silchenko,A.S., Dmitrenok, P.S. 2004. Structure of the major triterpene glycoside from the sea cucumber ''Stichopus mollis'' and evidence to reclassify this species into the new genus ''Australostichopus''. Biochemical Systematics and Ecology. 32 (7): 637–650. commonly known as the brown sea cucumber or Australasian sea cucumber. This species has stimulated interest for its fishery potential in the Southern Hemisphere,Stenton-Dozey, J. and Heath, P. 2009. A first for New Zealand: culturing our endemic sea cucumber for overseas markets. Water & Atmosphere .17(1). and for its capability to reduce waste produced by
aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...
. Despite its ecological role and abundance in New Zealand coastal waters, the scarcity of knowledge regarding ''A. mollis'' biology and ecology has hindered the development of a stable
fishery Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish far ...
industry. Importantly, ''A. mollis'' represents promising business potential within an important Asian market.Morgan, A. & Archer, J. 1999. Overview: Aspects of sea cucumber industry research and development in the South Pacific. SPC Beche-de mer Information Bulletin. 12. Recently its potential as a
functional food A functional food is a food claimed to have an additional benefit beyond just nutrition (often one related to health promotion or disease prevention) by modifying the horticulture, cultivation of the native food or by food additive, adding ingr ...
has been evaluated, highlighting the nutritious components


Distribution

In New Zealand, ''A. mollis'' is found around the entire coast line of the country, sometimes co-existing with reef structures;Slater, M.J. & Jeffs, A.G. 2010. Do benthic sediment characteristics explain the distribution of juveniles of the deposit-feeding sea cucumber ''Australostichopus mollis''?. J. Sea Res. . and from
New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...
to south
Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...
. The species principally inhabits the
littoral The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely i ...
at
low tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables c ...
level on sand, as well as in mud in protected areas. Their vertical range goes from shallows waters on the coast to around 200 metres of depth.Dawbin, W. H. 1950. A Guide to the Holothurians of New Zealand. Tuatara: Journal of the Biological Society. Vol. 3. Issue 1.Dawbin, W.H. (1948a). Auto-evisceration and regeneration of the viscera in the holothurian Stichopus mollis (Hutton). Transactions of the Royal Society of New Zealand. 77(4): 497–523


Anatomy

Adult size is typically from 13 to 25 cm.Sewell, M.A. 1990. Aspects of the ecology of Stichopus mollis (Echinodermata: Holothuroidea) in north-eastern New Zealand. NZ J. Mar. Freshw. Res. 24: 97–103. Body is soft, and colour varies from light mottled brown to black. A tube foot is present
ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
ly or extending up the whole body.
Tentacles 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 ...
(20) with disc shaped tips surround the slit-like mouth. Retractor muscles are absent. Dorsally, ''A. mollis'' has pointed papillae which can be reduced on preservation.


Feeding

Described as
detritivores 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, ...
, ''A. mollis'' mainly capture particles of
organic matter Organic matter, organic material or natural organic matter is the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have come fro ...
from the substrata, which is highly nutritious.Slater, M.J. & Carton, A. G. 2009. Effect of sea cucumber (''Australostichopus mollis'') grazing on coastal sediments impacted by mussel farm deposition. Marine Pollution Bulletin. 58: 1123–1129.


Reproduction

Via
sexual reproduction Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote tha ...
, and sexes are generally separate, however some
hermaphrodites A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...
have been found. Population
sex ratio A sex ratio is the ratio of males to females in a population. As explained by Fisher's principle, for evolutionary reasons this is typically about 1:1 in species which reproduce sexually. However, many species deviate from an even sex ratio, ei ...
is 1:1. Reproductive season is from October to February,Sewell, M. A. and P. R. Berquist. 1990. Variability in the reproductive cycle of Stichopus mollis (Echinodermata:Holothuroidea). Invertebrate Reproduction and Development. 17(1):1–7. and periodicity of
spawning Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...
is regulated by lunar cycles, specifically following a full moon.Morgan, A. 2009. Spawning of the Temperate sea cucumber, ''Australostichopus mollis''(Levin). Journal of the World Aquaculture Society. Vol. 40. No. 3. Morphologic changes in reproductive periods include females changes in
gonad A gonad, sex gland, or reproductive gland is a Heterocrine gland, mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gon ...
colour and
oocyte An oocyte (, oöcyte, or ovocyte) is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ger ...
numbers, while in males there is an increase in the amount of
spermatozoa A spermatozoon (; also spelled spermatozoön; : spermatozoa; ) is a motile sperm cell (biology), cell produced by male animals relying on internal fertilization. A spermatozoon is a moving form of the ploidy, haploid cell (biology), cell that is ...
in particular zones described as "wet mounts of 'mashed' gonad tissue". Furthermore, there is an increase in
spermatozoa A spermatozoon (; also spelled spermatozoön; : spermatozoa; ) is a motile sperm cell (biology), cell produced by male animals relying on internal fertilization. A spermatozoon is a moving form of the ploidy, haploid cell (biology), cell that is ...
in the lumen of histological sections. Studies suggest that
spawning Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...
may occur repeatedly during a single reproductive season.


Auto-evisceration

Like other
holothurians Sea cucumbers are echinoderms from the class Holothuroidea ( ). They are benthic marine animals found on the sea floor worldwide, and the number of known holothuroid species worldwide is about 1,786, with the greatest number being in the Asia†...
, ''A. mollis'' has the ability to regenerate its internal organs after undergoing a phenomenon called auto-
evisceration Evisceration (pronunciation: /ɪvɪsəˈreɪʃən/) is disembowelment, i.e., the removal of viscera (internal organs, especially those in the abdominal cavity). The term may also refer to: * Evisceration (autotomy), ejection of viscera as a defen ...
. This process, which is thought to be induced by external stimuli, is characterized by violent and rapid expulsion of organs, followed by regeneration, which occurs at a slower rate than in other
genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...
. Nevertheless, a more recent study reports no spontaneous evisceration or seasonal atrophy of the viscera, highlighting that handling these organisms does not trigger such reactions and even suggesting than during
predation Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
it would not occur easily.


Predation

Available information posits the existence of just one predator: the
starfish Starfish or sea stars are Star polygon, star-shaped echinoderms belonging to the class (biology), class Asteroidea (). Common usage frequently finds these names being also applied to brittle star, ophiuroids, which are correctly referred to ...
'' Luidia varia'', observed in two cases. To date there is no evidence to suggest any fish or other organism preying on ''A. mollis''.


Juveniles

Juveniles are distributed in the shallow sub-tidal zone (5–8 m of depth), relatively close to where adults are concentrated. However, they are usually found in a different substrata; one of smaller grain size, and associated to macroalgae as initial settlement, where they obtain detritus and protection from predators. These factors are thought to drive distribution, rather than and food type and availability. Experimental data shows high survival rates of juveniles using a natural diet, and still higher rates in a mussel waste medium. Thanks to attempts to produce juveniles in a commercial scale a better understanding of early post-settlement juveniles' growth and pigmentation process has been achieved


Fishery

Processed sea cucumbers are traded under the name of ''beche-de-mer'', representing an important fishery in South Pacific and
Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...
n nations. In
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
, where its exploitation occurs on a small-scale, this species is under the New Zealand fisheries quota management system and is principally caught by free-diving. Sea cucumber yields can be very profitable if the resource is adequately processed, or if a value-added policy is implemented. Currently, due to the expansion of commercial exploitation of ''A. mollis'' in New Zealand and Australia, first attempts at massive culture are being carried out. A new approach to sea cucumber farming has been the so-called
polyculture In agriculture, polyculture is the practice of growing more than one crop species together in the same place at the same time, in contrast to monoculture, which had become the dominant approach in developed countries by 1950. Traditional example ...
, where sea cucumber are bred together with
mussels Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, whic ...
and
finfish Fishery can mean either the Big business, enterprise of Animal husbandry#Aquaculture, raising or Fishing, harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place (wikt:AKA, a.k.a., fishing grounds). ...
, consuming the wastes from nearby farming as a food supply, and at the same time providing new products. Trials farming sea cucumber with
abalone Abalone ( or ; via Spanish , from Rumsen language, Rumsen ''aulón'') is a common name for any small to very large marine life, marine gastropod mollusc in the family (biology), family Haliotidae, which once contained six genera but now cont ...
have shown not to be biologically viable.


Larvae development

The complete
larvae A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect developmental biology, development such as insects, some arachnids, amphibians, or cnidarians typical ...
stage takes approximately 21 days. After
fertilization Fertilisation or fertilization (see American and British English spelling differences#-ise, -ize (-isation, -ization), spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give ...
there are seven stages of larva metamorphosis: cleavage, blastocyst, gastrulation, auricularia (subdivided in early, mid, late), doliolaria (mid metamorphic stage pre settlement), penttactula and the last settled sea cucumber larva, visible to the naked human eye, which develops into the final organism.Morgan, A. 2009. Spawning of the Temperate Sea Cucumber, Australostichopus mollis (Levin). Journal of the World Aquaculture Society. Vol. 40. No. 3


Polycultures

Considering the detritus-feeding characteristic of
holothurians Sea cucumbers are echinoderms from the class Holothuroidea ( ). They are benthic marine animals found on the sea floor worldwide, and the number of known holothuroid species worldwide is about 1,786, with the greatest number being in the Asia†...
, and their role on coastal marine systems, several studies have focussed on their
grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to free range (roam around) and consume wild vegetations in order to feed conversion ratio, convert the otherwise indigestible (by human diges ...
effect on
sediments Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...
. These studies have calculated declines in
total organic carbon Total organic carbon (TOC) is an analytical parameter representing the concentration of organic carbon in a sample. TOC determinations are made in a variety of application areas. For example, TOC may be used as a non-specific indicator of wa ...
and
chlorophyll Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words (, "pale green") and (, "leaf"). Chlorophyll allows plants to absorb energy ...
a and phaeopigment accumulation, positioning ''A. mollis'' as an effective tool to avoid, restore and control pollutive impacts of coastal
bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...
aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...
. In terms of evaluating the feasibility of polycultures, this has been evaluated in the field under Greenshell mussel and Pacific oysters' farms.Zamora, L.N., Dollimore, J. and Jeffs, A.G., 2014. Feasibility of co-culture of the Australasian sea cucumber (''Australostichopus mollis'') with the Pacific oyster (''Crassostrea gigas'') in northern New Zealand. New Zealand Journal of Marine and Freshwater Research, 48(3), pp.394–404. In land based systems, according to the energetic requirements of adult sea cucumbers, results have inferred that waste production of an industry standard-type abalone lacks sufficient energy to meet ''A. mollis'' metabolic needs. However, there is suggestion that feeding juveniles from these wastes could be feasible.Maxwell, K., Gardner, J.P.A., Heath, P., 2009. The effect of diet on the energy budget of the brown sea cucumber, ''Stichopus mollis'' (Hutton). J. World Aquac. Soc. 40: 159–170. Conversely, waste generation from fresh mussels have proven to be the source of enough energy to sustain juvenile stocks, assuming a suitable scale to ensure the supply. Sea cucumbers also have been used as
bioremediation Bioremediation broadly refers to any process wherein a biological system (typically bacteria, microalgae, fungi in mycoremediation, and plants in phytoremediation), living or dead, is employed for removing environmental pollutants from air, wate ...
units in scenarios of high organic waste pollution from farming, such as
salmon Salmon (; : salmon) are any of several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the genera ''Salmo'' and ''Oncorhynchus'' of the family (biology), family Salmonidae, native ...
. In this instance, this carbon source is transformed into body tissue; an example of efficiently using supplies and producing an alternative culture.


References

{{Taxonbar, from=Q4305674 Monotypic echinoderm genera Holothuroidea genera Stichopodidae