Gut fish

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Gut fish
Carapus acus

Carapus acus

Systematics
Acanthomorphata
Spinefish (Acanthopterygii)
Perch relatives (Percomorphaceae)
Order : Viscera (Ophidiiformes)
Subordination : Ophidioidei
Family : Gut fish
Scientific name
Carapidae
Jordan & Fowler , 1902

Visceral fish (Carapidae) live in tropical and subtropical regions of the Atlantic , Pacific and Indian Oceans at depths of up to 2000 meters. Echiodon drummondii also lives in the North Sea . They got their German name because some species hide in the body cavities of invertebrates .

features

Visceral fish are eel-like, elongated, the body is scaly and often transparent. The dorsal and anal fin form seams along the top and bottom of the body, which is pointed at the end, whereby the fin rays of the anal fin are always longer than the opposite fin rays of the dorsal fin. Ventral fins are always missing, the pectoral fins only in three species of the genus Encheliophis . The anus and genital opening are very far in front, directly behind the head, below the pectoral fins, at the front end of the anal fin. The gill openings are large and reach far forward, there are six to seven gill traps. In addition to the jaws, the ploughshare and the palatine bone are also dentate. Visceral fish grow to be seven to 36 centimeters long.

Way of life

Visceral fish can live freely ( Echiodon , Eurypleuron ) or together with sea ​​cucumbers , starfish , clams or sea ​​squirts as commensals ( Carapus , Onuxodon ) or possibly as parasites ( Encheliophis ). The fish penetrate the host first with the tail or head-on and can also live in it in pairs.

Gut fish eat small invertebrates and fry. It is controversial whether some species, as is often claimed, eat the internal organs of their hosts.

The eggs of the intestinal fish are pelagic , the larvae, which are also pelagic, first go through a stage called vexillifer , in which they carry a long appendage with three to eight leaf-like appendages. The next larval stage is called Tenuis . This relatively long larval form melts the vertebral bodies from back to front and uses the released nutrients and the like. a. for the formation of otoliths . Tenuis larvae live on the sea floor, they already resemble adult fish. The head is still quite small relative to the body and has not yet reached its full length. At this stage, intestinal fish colonize their host.

Systematics

There are 35 species in seven genera and three subfamilies:

Subfamily Carapinae

In the subfamily Carapinae, the pectoral fins are shorter than the length of the head and have 23 or fewer fin rays. The upper jaw is not protractile (cannot be extended). The number of precaudal vertebrae (all vertebrae except caudal vertebrae) is 17 to 35.

Carapus dubius
Echiodon rendahli , vexillifer larva
Echiodon rendahli , adult
Encheliophis homei

Subfamily Pyramodontinae

Pyramodon ventralis
Snyderidia canina

In the subfamily Pyramodontinae, the pectoral fins are as long as the length of the head and are supported by 24 to 30 fin rays. The upper jaw is protractile (can be extended). The number of precaudal vertebrae is 12 to 15.

Subfamily Tetragondacninae

The only species of the subfamily Tetragondacninae differs in numerous characteristics, e.g. B. their scaling of other intestinal fish.

swell

further reading

  • Parmentier Eric et al .: Remodelling of the vertebrate axis during metamorphic shrinkage in pearlfish. (2003), Journal of Fish Biology, Volume 64 Issue 1, Pages 159 - 169. doi : 10.1111 / j.1095-8649.2004.00294.x

Web links

Commons : Carapidae  - collection of images, videos and audio files

Individual evidence

  1. ↑ Brooke Luciano, Ashleigh Lyman, Selena McMillan, Abby Nickels: The symbiotic relationship between Sea cucumbers (Holothuriidae) and Pearlfish (Carapidae) . Text on the symbiotic relationship between sea cucumber and gut fish PDF