What is it?

[wasp]

Saw this, about the size of a 50 cent piece or a tad smaller.

It looked like, and i thought it might be, a baby urchin.

But when I touched it with some tongs, Pow! it was gone in a flash, into the rock. Definately not an urchin. The spike things seemed hard to the touch. Sorry about the crude pic, with my limited skills it's the best i could get.

[tHEcONCH]

I don't know, but kind of cool!

[Fmxmatt]

I've got one of those in my tank aswel, but its clear. Noticed it one day when I was feeding as it grabbed food and disappeared, then reappeared kind of like a balloon being blown up

[Guest]

They look cool.

[evilknieval69]

Its not a nudibranch or something of that kind?

[cookie extreme]

its a sea cucumber. keep an eye on it. it must have come in as a hitch hiker (you importing stuff from china via middle man again? ). but do watch it it will move around quite a bit and cover your power head inlets too.

[cookie extreme]

most likely H. leucospilota

[wasp]

I thought cucumbers moved slowly. This thing dissapeared in the blink of an eye.

[chimera]

possibly the head of a seacucumber, similar shape to the head of this one:

[wasp]

Thanks for that i think you may be right, what i saw could have been one of those little appendage things as per your pic. There would have been room how the rock is placed for a bigger thing to be hidden inside it.

Do you ever see these sea cucumbers or do they hide all the time?

[wilson]

thats cool

wasp has it moved or have you seen it out of the rock?

[wasp]

Haven't seen it since. Going by that pic of Chimeras, it must have been in the tank and taken quite a while to get to that size, as the bit I saw was just a small part of it, so it must be a fairly secretive animal.

Maybe I'll see it again in another few years.

[wilson]

lol i love that about marine tanks

[slappers]

[wasp]

most likely H. leucospilota

Well thanks Cookie very interesting. I've done a bit of Googling on this and think you are right, i also think it probably arrived in my tank as a tiny one perhaps many years ago.

Found out some interesting stuff, not the least being that their gonads are regarded as a prime delicacy in Tonga. You were a chef there Cookie, right? :lol:

here's some other interesting stuff

1.

A new triterpene glycoside from sea cucumber Holothuria leucospilota

Hua Hana, Yang Hua Yi, a, , Ling Lia, Xiao Hua Wanga, Bao Shu Liua, Peng Suna and Min Xiang Pana

aResearch Center for Marine Drugs, School of Pharmacy, Second Military Medical University, Shanghai 200433, China

Received 30 August 2006. Available online 23 January 2007.

Abstract

A new triterpene glycoside, leucospilotaside A, along with a known saponin, isolated from sea cucumber Holothuria leucospilota, and its structure was elucidated as 3β-O-[4-O-sodiumsulfate-β-d-quinovopyranosyl-(1 2)-β-d-xylopyranosyl]-holosta-22-ketone-9-en-17α,25α-diol (1) by extensive spectroscopic analysis and chemical methods. Leucospilotaside A (1) has a ketone carbonyl group (22) in the aglycon side chain.

2.

Biomechanics of Adhesion in Sea Cucumber Cuvierian Tubules (Echinodermata, Holothuroidea)1

Patrick Flammang2,,1, Jérôme Ribesse1 and Michel Jangoux1,2

1 Marine Biology Laboratory, University of Mons-Hainaut, 6 Avenue du Champ de Mars, B-7000 Mons, Belgium

2 Marine Biology Laboratory, Free University of Brussels, 50 Avenue F.D. Roosevelt, B-1050 Brussels, Belgium

Several species of sea cucumbers, all belonging to a single family, possess a peculiar and specialized defense system, the Cuvierian tubules. It is mobilized when the animal is mechanically stimulated, resulting in the discharge of a few white filaments, the tubules. In seawater, the expelled tubules lengthen considerably and become sticky upon contact with any object. The adhesiveness of their outer epithelium combined with the tensile strength of their collagenous core make Cuvierian tubules very efficient at entangling and immobilizing most potential predators. We have designed a method to measure the adhesion of holothuroid Cuvierian tubules. Tubule adhesive strength was measured in seven species of sea cucumbers belonging to the genera Bohadschia, Holothuria and Pearsonothuria. The tenacities (force per unit area) varied from 30 to 135 kPa, falling within the range reported for marine organisms using non-permanent adhesion. Two species, H. forskali and H. leucospilota, were selected as model species to study the influence of various factors on Cuvierian tubule adhesive strength. Tubule tenacity varied with substratum, temperature and salinity of the seawater, and time following expulsion. These differences give insight into the molecular mechanisms underlying Cuvierian tubule adhesion. Tenacity differences between substrata of varying surface free energy indicate the importance of polar interactions in adhesion. Variation due to temperature and time after expulsion suggests that an increase of tubule rigidity, presumably under enzymatic control, takes place after tubule elongation and reinforces adhesion by minimizing peeling effects.

3.

Sea cucumber habits

Sea cucumbers in the four island groups are found on the coral reef flats at up to 70 m depth. Some species, such as T. ananas, H. nobilis and B. argus, live among coral reefs while others seek shelter in sandy bottoms and among the seaweed. Some species live in shallow waters near the sublittoral zone, such as A. mauritiana and H. cinerascens; some live in areas with an abundance of sand and seaweed, such as A. echinites, H. atra, H. edulis and S. hermanni; some prefer areas affected by a strong wave action, such as A. miliaris and H. scabra; while others prefer calm waters, such as S. chloronotus, A. lecanora, H. nobilis and B. marmorata and they are mostly found in deep waters (40-60 m). T. ananas, A. lecanora, B. argus and A. mauritiana are distributed in waters between 10 to 50 m depth. H. atra, H. leucospilota and S. hermanni all live in shallower waters, up to 15 m in depth.

Generally, sea cucumbers stop feeding and burrow in the sand at midnight and burrow when the water temperature is low (Li, 1990). Many species emerge from the sand at dawn and feed from noon to dusk. Sea cucumbers feed on organic matter and microorganisms, such as diatoms, foraminifera, radiolarian, small crustaceans and gastropods typically found in the sand (Li, 1990). Some species of sea cucumber, for example T. ananas and B. argus, have symbiotic fish in their cloacae. The internal organs of sea cucumber can generally regenerate if body is cut in two.

Tools and fishing methods

Fishing for sea cucumber is a traditional activity among the local fishers in Qionghai, Hainan. According to local historical records, sea cucumber fishing in Xisha, Zhongsha and Nansha islands started in 1681 and has continued from generation to generation without interruption.

Collections relied on free diving and capture of sea cucumbers by hand in the early periods, so the fishing grounds were restricted to waters with a maximum depth of 20 m. At some point, however, fishermen became unhappy with the collection efficiency as it was impossible to capture the larger specimens living in deeper waters. As a result, a tool known as the “sea cucumber fork†was designed and used in the 1920s to capture sea cucumbers. The fork was subsequently improved and nowadays it consists of a fork, a weight, a rope and a buoy (Figure 1).

The specifications of these components are as follows:

1) Fork: the fork is made of steel with sharp agnail ends. The pointed elements of the fork are arranged in a triangular fashion and secured at one end of a cylindrical weight. The pointed elements are 11 cm in length and 1 cm in diameter and fixed 6 cm apart from one another. The sharp ends are 3.7 cm in length and 0.8 cm in width.

2) Weight: The cylindrical element is a 9 kg lead weight with a diameter of 9.5 cm.

3) Rope: the rope is usually 80 m in length.

4) Buoy: the buoy is made of plastic with a buoyancy of 20 kg.

The boats used in sea cucumber fishing are generally 50-80 tonnes, in gross tonnage, fitted with a 120-250 hp engine and generally have 12-16 people onboard. Each support vessel usually carries 3 to 4 smaller boats (15-25 hp, 3-5 gross tonnage each) to enable the divers to easily move around the reefs. At the fishing grounds the collection of sea cucumbers is carried out using the smaller boats which carry a crew of 3; one in charge of steering the boat while the other two engage themselves in fishing with the use of masks or “view bucketsâ€. Upon detection of the sea cucumbers on the sea bottom the divers enter the water and swim directly above the animal. Fishing is carried out by dropping the fork on the specimen seen by the diver. One end of the fork rope is attached to the boat in order to facilitate the retrieval of the captured sea cucumber. Because of the relative seawater turbidity around the islands the fishing activity is generally restricted in waters not deeper than 60 m. Commonly 20 kg of sea cucumbers, such as T. ananas, are collected by each boat (or 2 000 kg/year). Furthermore, fishermen engaged in the collection of sea cucumber very often fish for other species such as sharks, molluscs, as well as collect a variety of seaweed species.

Figure 1. The traditional tool used for fishing tropical sea cucumbers (“Drawings of Chinese Fishing Tools†published in 1989).

Processing methods

The processing of sea cucumbers involves three steps: removal of the viscera, cooking and drying.

Prior to the evisceration process the sea cucumbers are sorted by species. In the case of T. ananas the incision is made on the ventral side, while it is done on the dorsal side for all other large species. In the smaller species a small incision in done beside the mouth. Following the removal of the internal organs the sea cucumbers are rinsed with seawater and then placed in a suitable boiler. Small individuals are cooked for 30 minutes, while larger individuals may require an additional 10-15 minutes. The optimal water temperature when cooking species such as H. nobilis and B. marmorata is around 90 °C. During this phase the sea cucumbers become stiff and lose 50-70 % of their body fluids, assuming a yellowish colouration in species like T. ananas and S. hermanni, and blackish colouration in most other species. The sea cucumbers are then rinsed again once they are removed from the hot water. Large species, such as T. ananas, H. nobilis and B. marmorata, are further baked over hot coals for an additional 30 minutes. The cooked product is then sun dried (small bamboo sections are used to keep the incision wide open in large individuals) while ensuring that each sea cucumber is regularly turned over every few hours. Up to 3-5 days may be required to dry the products completely.

Proper cooking and drying of sea cucumbers is essential. If not cooked completely the sea cucumber will soon start to rot and acquire an undesirable smell. Overcooking may also damage the product as a very soft sea cucumber may not be processed into a high quality product. Fishers in Qionghai have acquired considerable processing experience over the years and tend to produce a higher quality product compared to that produced in some neighbouring countries.

The ratio of dry weight to wet weight of the processed sea cucumber is 27:1 in H. nobilis and H. leucospilota, 25:1 in T. ananas, 20:1 in S. hermanni and S. chloronotus, 17:1 in A. lecanora, B. argus and A. mauritiana and 10:1 in H. nobilis and B. marmorata.

Nutritional value and cooking method

Sea cucumber is a nutritious seafood with a high protein and low lipid content and is rich in gluten, nitrogen, iodine and other nutritional elements (Wang, 1997). The protein content of a dried sea cucumber may be as high as 68.7 %. Considered as one of the most popular Chinese seafood dishes, sea cucumbers are also used as a traditional medicine. It is believed that the consumption of this marine organism may have beneficial effects on the kidneys and stomach as well as being a cure for some cancers. Some research findings report that sea cucumbers have helped impotent individuals as well as patients affected by other sexual conditions (Ran, 1993). In the culinary tradition, sea cucumbers are prepared and consumed in a variety of ways. Some of the most popular dishes are: sea cucumber stew, braised sea cucumber, boiled sea cucumber, lotus seed-sea cucumber and chicken-sea cucumber soups.

4.

Holothuria leucospilota in the Cook Islands and the implications of traditional fishing of gonads on the population

Darrin J. Drumm1,2

Neil R. Loneragan2,*

1Department of Marine Science

University of Otago

Dunedin, New Zealand

email: [email protected]

2CSIRO Marine Research

Cleveland Marine Laboratories

Cleveland

QLD 4163, Australia

*Present address: Centre for Fish and Fisheries, Murdoch University, Murdoch, WA 6150, Australia.

Abstract This study describes the reproductive biology of Holothuria leucospilotain Rarotonga, Cook Islands and assesses the effect of traditional fishing on survival and reproduction. Monthly collections of H. leucospilota from January 1998 until March 1999 revealed that gametogenesis and spawning were synchronous between the sexes and spawning occurred annually during the summer months. Spawning during the first year had already started at the beginning of the study in January and lasted until April, whereas in the second year, spawning started in November and finished in February, possibly because of higher water temperatures in this year. Our data indicate that the incision of the body-wall and gonad removal had no impact on the survival of H. leucospilota in cages. However, their body weight, general sheltering and feeding behaviours were affected by gonad removal. Although the body-wall of fished animals healed within 7-14 days, the gonads had just started to regenerate after 41 days, suggesting that the spawning of fished individuals would have been greatly delayed, possibly until the following year.

And there's much more but didn't want to wear you all out!