| Biological Diversity 2001 | |
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Photo courtesy of the Darwin Foundation. Kingdom:
Animalia
Phylum: Echinodermata Class: Holothuroidea
Conservation Organizations Darwin
Foundation Secreteriat
of the Pacific Community
Beche-de-mere made from Holothuroidea scabra. Image courtesy of SPC.
Image
courtesy of http://www.polaris.net/sui/jpinson/pml/gal/pepino/pepino.html
Literature Cited Charles
Darwin Research Station. copyright 2000- 2001. www.darwinfoundation.org
Home page. Accessed November
12, 2001. World
Wildlife Fund. copyright 1995-2001. www.wwf.org
Home page. Accessed November 12, 2001.
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Holothuroidea Introduction Sea cucumbers
(Holothuroidea) include more than 1100 species of marine organisms worldwide.
They make up an ancient group; modern cucumbers are the results of 540
million years of evolution from their original appearance in the ocean
(Lambert, 1995). These slug-like creatures suit their environment well.
Their bodies are cylindrical, with a mouth and anus at opposite ends.
Retractable tube feet and tentacles allow feeding and movement along the
sea floor. When encountering a predator, sea cucumbers will commonly expel
their organs as a distraction. They have a supply of backup organs and
the ability to regenerate those that are lost (Columbia Electronic Encyclopedia,
2000). Conservation Status No species of sea cucumber is listed on the ICUN red list. Upon examining the criteria, it is possible they have been omitted due to lack of research, or because although there are species threatened in a regional area but no species' global population is threatened.
Image courtesy of The Darwin Foundation Conservation Issues In many Asian markets, the sea cucumber has historically been fished and consumed as a delicacy, and in recent times the demand has skyrocketed. More and more, the large world markets - Japan, Hong Kong, Taiwan, and Singapore - which export to smaller consumer markets, have turned to fisheries outside of Asian waters as their own stocks have become depleted (Conand 1999). Of the approximately 1250 species of Holothuroidea worldwide, only a handful are commercially exploitable or are so at this time (nearly all of these are from the order Aspidochirotida), and these are suffering from the pressures of commercial fishing operations. Some of the major fisheries that have been the focus of recent attention are those off the coasts of Baja California, Eastern Russia, and the Galapagos Archipelago. In Baja California, harvesting of the sea cucumber Isostichopus fuscus (Family: Stichopodidae, Order: Aspirochirotida) for export to Asian markets rose very sharply between between 1985 and the mid nineties, and in May of 1994 they were declared in danger of extinction by the National Institute of Ecology of Mexico (Castro 1995). The sessile and therefore easily harvested. Cucumaria japonica (Family: Cucumaridae, Order: Dendrochirotida) has historically been fished in the seas of Eastern Russia for both food and cosmetic products. Like other species, these cucumbers contain chemicals called triterpine glycosides which have may possible commercial uses, and fishing - done by bottom trawling - is increasing annually well beyond the legal 50 ton catch limit (Levin 1995). Overfishing of sea cucumbers very often correlates with local socioeconomic problems. In 1989, sea cucumber fishermen from mainland Ecuador naming themselves pepineros arrived in the Galapagos and began setting up operations, the fisheries off the coast of Ecuador being nearly depleted. There was no sound biological basis for establishing a fishery there, nor any management plan enacted that might have regulated the fishing practices of the pepineros (Martinez 2001). Populations of the sea cucumber Stichopus fuscus (Family: Stichopodidae, Order: Aspirochirotida) became dramatically reduced almost immediately, and this coupled with the increased migrations of people to the Galapagos prompted a ban on all harvesting of sea cucumbers. Illegal fishing continued, however, and in early 1994, the pepineros began slaughtering tortoises and sea lions as a protest against the ban, and under pressure from environmental groups the ban was lifted. It was not until Ecuador passed the Galapagos Marine Management Plan in 1999 that harvesting of sea cucumbers became regulated under a concrete legal and conservation framework. The successive fishing seasons have shown marked increases in sustainability, though problems with the pepineros killing and kidnapping tortoises continue (Martinez 2001). Research into sea cucumber reproduction has shown that because they are broadcast spawners, populations with low density tend to increase only slowly. In the Torres Strait, where overfishing has reduced populations of sandfish or Holothuroidea scabra (Family: Holothuroidea, Order: Aspidochirotida), the Australian government is exploring the possibility of 'seeding' depleted fisheries with hatchery-raised juveniles, but as yet has not begun a wide scale program (D'Silva 2001). Sandfish have proved an important candidate for research into artificially repopulating fisheries due to its hardy and resilient larvae, and more so because it is one of the most highly prized and thus overfished of the sea cucumbers (Battaglene 1999). The dangers in losing
large numbers or even entire populations of sea cucumbers is that within
their ecosystems they are some of the primary detritus feeders, consuming
and pulverizing organic matter so that it may be easily broken down by
bacteria. Without them, the quality of the substrate may be severely reduced;
in some areas of the world, overfishing of sea cucumbers has caused the
hardening of the sea floor, leaving it uninhabitable to many other bottom-dwelling
organisms (Darwin Foundation 2001). Biodiversity in many marine ecosystems
is thus heavily dependent on the presence of healthy populations of sea
cucumbers.
Image courtesy of The Darwin Foundation
Authors: Lucy Beirne,
Katie Fitzmier, Matt Miller |
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Acanthaster planci • Apis mellifera • Capybara • Chimpanzee • Danaus plexippus • Exciting Cephalopods • Green Sea Turtle (H-R,K) • Green Sea Turtle (B,M,C) • Green Serpent Star • Holothuroidea • Hyenas • Latimeria chalumnae • Mudpuppy • Northern Leopard Frog • Pink Seafan • Salamanders • Scyphozoa • Tuatara This website is part of a Biology 26 class project on the conservation of global biodiversity. |
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Earlham · Biology Department · Biology 26 : Biological Diversity |
