Wednesday, 19 October 2011

Sea Pigs

A sea pig of the scotoplanes globosa species
A sea pig
Species: Scotoplanes Globosa
Kingdom: Animalia
Phylum: Echinodermata
Class: Holothuroidea
Order: Elasipodida
Family:  Elpidiidae
Genus: Scotoplanes
Conservation Status: Not Evaluated
Common Names: Sea pigs, sea cows



Sea pigs are deep sea holothurian echinoderms of the Scotoplanes genus. They can be found in deep ocean bottons all over the world, specifically on the abyssal plain in the Atlantic, Pacific and Indian Ocean, usually at depths of 1000 meters or greater.

They are closely related to sea cucumbers (Holothuroidea). They are also known as sea cows because of the tube feet on their upper body side, which are reminiscent of cattle horns. Sea pigs haven't been thoroughly studied and thus little is known about them.

Sea pig video


Species
Currently, there are 5 described scotoplanes species:
  • Scotoplanes clarki  
  • Scotoplanes globosa  
  • Scotoplanes hanseni 
  • Scotoplanes kurilensis  
  • Scotoplanes theeli  

Description
The average sea pig  has a fat, oval body, with a length ranging from 5 to 10 cm (2 to 4 inches). The mouth is surrounded by ten feeding tentacles and they have five to seven pairs of feet, that are used exclusively for walking on the sea bottom.

They have three pairs of papillae on the upper surface of the body. The two are long and whip-like, but the third pair is short and inconspicuous.

Enemies
Sea pigs are a common host for various parasitic organisms including:
  • Gastropods(snails of genus Stilapex)
  • Small tanaid crustaceans (Tanaidacea)

Image of a sea pig infested by a sea snail
Sea pig infected by a sea snail
Credit: S. Schiaparelli

The snails make small holes into the body wall and suck on their juices. Similarly, the small tanaid crustaceans drill small holes and  feed on the internal organs.

Behaviour
Scotoplanes are known to form large groups. There have been reports of groups comprised of more than 1.000 individuals while early trawling records indicate an average of 300-600 caught specimens per trawl.

It is believed that sea pigs are not actually social animals. They simply gather where food resources are abundant.

They live on the ocean's bottom, at depths of 1000 meters (3200 feet) or deeper. Specimens have been collected from depths of over 6000 meters (19685 feet).

Diet
Sea pigs are deposit feeders that obtain their food by extracting organic particles from deep-sea mud. They have a high preference for rich and organic sources that have recently fallen from the ocean's surface (e.g. a dead whale). They mainly use their sense of smell to detect their food. This is why they are commonly found facing towards the prevailing currents.

They use the ring of tentacles that surrounds the mouth to feed and absorb nutrients.

Threats and conservation status
Their conservation status has yet to be officially evaluated, however they are not believed to be threatened due to their global distribution and their seemingly abundant numbers.

Their biggest threat is deep sea trawling as the average trawler, sweeps, catches and obviously kills, 300 to 600 sea pigs. Perhaps trawling may pose a serious problem in the future.


Sea pigs east of Endeavour ridge (depth: 2324m)

Sea Pigs as pets
Well, they are cute and surely there are many people wanting to get one as pet. However, duplicating the temperature and high pressures of their habitat is very difficult. Not to mention that you are gonna need  a trawler or a sub to catch one. Good luck with that !

Interesting Facts about sea pigs
- There are other genera of Elpidiidae with a similar appearance that are also referred to as "sea pigs". One notable example is Protelpidia murrayi, which occurs in the shallower waters off Antarctica. Some species of porpoise, dolphin, or dugong are also called sea pigs.

Image of a sea pig (Protelpidia murrayi)
Protelpidia murrayi
Credit:  W. Arntz


References & Further Reading
- Théel, H (1886). Report on the Holothurioidea dredged by HMS Challenger during the years 1873-76.
- Hansen, B. (1972). Photographic evidence of a unique type of walking in deep-sea holothurians Deep Sea Research and Oceanographic Abstracts, 19 (6) DOI: 10.1016/0011-7471(72)90056-3
- Miller, R., Smith, C., Demaster, D., & Fornes, W. (2000). Feeding selectivity and rapid particle processing by deep-sea megafaunal deposit feeders: A 234Th tracer approach Journal of Marine Research, 58 (4), 653-673 DOI: 10.1357/002224000321511061
http://www.marinespecies.org/aphia.php?p=taxdetails&id=123520

9 comments:

  1. We enjoyed reading this article very much. Thank you for putting it on here. Liberty and Pete.

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  2. This is an awesome animal

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  3. FREAKING COOL TYPE OF PIG

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  4. NO ITS NOW THIS IS INTRESTING

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  5. awesomeeeeeeeeeeeeeeeeeee

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  6. It is very interesting. I would like to know how do they reproduce?

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  7. how do they sleep?

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