Gobiidae
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| Family: | Gobiidae
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The Gobies form the family Gobiidae, and is one of the largest families of fish, with over 2000 nominal species. Most are relatively small, typically less than 10 cm (4 in) in length. Gobies include some of the smallest vertebrates in the world, like species of the genera Trimmaton, Tyson and Pandaka, which are under 1 cm (3/8 in) long when fully grown. Up to 2005 the smallest described vertebrate was the goby Schlinderia brevipinguis (Watson & Walker, 2004), but seemingly this guinness has been beaten by the cyprinid Paedocypris progenetica (Kottelat. et al., 2005), whose smallest mature female measured was a mere 7.9mm. There are some large gobies, such as species of Gobioides, that can reach well over 30 cm (1 ft) in length, but that is exceptional. Although few are important as food for humans, they are of great significance as prey species for commercially important fish like cod, haddock, sea bass, and flatfish. Several gobies are also of interest as aquarium fish, in particular the bumblebee gobies of the genus Brachygobius.
The most distinctive aspect of goby morphology are the fused pelvic fins that form a disc-shaped sucker. In function this sucker is analogous to the dorsal fin sucker possessed by the remora or the pelvic fin sucker that the lumpfish has, but is anatomically a quite distinct structure, and thus any similarities are the product of convergent evolution. Gobies can often be seen using the sucker to adhere to rocks and corals, and in aquaria they will happily stick to glass walls of the tank as well.
Gobies are primarily fish of shallow marine habitats including tide pools, coral reefs, and seagrass meadows; they are also very numerous in brackish water and estuarine habitats including the lower reaches of rivers, mangrove swamps, and salt marshes. A small number of gobies (unknown exactly, but in the low hundreds) are also fully adapted to freshwater environments. These include the Asian river gobies (Rhinogobius spp.), the desert gobies of Australia (Redigobius), and the European freshwater goby Padagobius martensii.
The "sleeper gobies" (Eleotridae) are a closely-related family.
Mudskippers
Mudskippers are highly derived intertidal gobies, a group of species actually included in the subfamily Oxudercinae (Murdy, 1989). Mudskippers are tropical and subtropical species, whose geographical distribution includes all the Indo-Pacific region, plus the Atlantic African coasts. These gobies live out of water for extended periods (feed, interact, defend territories, etc.) through a combination of behavioural and physiological adaptations. These include: 1) locomotory anatomical and behavioural adaptations (Harris, 1961); 2) the ability to breathe through the skin of their body and the highly vascularised mucosae lining the inside of their mouth, opercula and pharynx (cutaneous breathing: Graham, 1997); and 3) the digging of burrows to thermoregulate, to avoid marine predators during the high tide (when the burrow is submerged) and to lay their eggs (Sasekumar et al., 1994; Tytler & Vaughan, 1983; Brillet, 1969a). Mudskippers maintain an air phase inside burrows to get access to oxygen in the highly anoxic conditions found inside burrows (Ishimatsu et al., 1998; 2000; Lee et al., 2005)
The genus Periophthalmus actually includes 17 morphospecies (Larson & Takita, 2005). Periophthalmus argentilineatus is one of the most widespread and well known mudskippers. This species can be found in mangrove ecosystems and mudflats of East Africa and Madagascar east through South East Asia to Northern Australia, Hong Kong and Japan, up to Samoa and Tonga Islands (Murdy, 1989). It grows to a length of about 6 in (15 cm) and is a carnivorous opportunist feeder. It feeds on small preys such as small crabs and other arthropods (Milward, 1974). Periophthalmus barbarus is the only oxudercine goby that inhabits the coastal areas of Western Africa (Murdy, 1989).
The literature cited is available here.
Edited by Gianluca Polgar (12/02/2006)
Symbiosis
Some goby species live in symbiosis with burrowing shrimps. The shrimp maintains a burrow in the sand in which both the shrimp and the goby fish live. The shrimp has poor eyesight compared to the goby, but if it sees or feels the goby suddenly swim into the burrow, it will follow. The goby and shrimp keep in contact with each other, the shrimp using its antennae, and the goby flicking the shrimp with its tail when alarmed. These gobies are thus sometimes known as 'watchman gobies'.
Another example of symbiosis is demonstrated by the neon gobies (Gobiosoma spp.). These gobies are cleaner fish, and remove parasites from the skin, fins, mouth, and gills of a wide variety of large fish. The most remarkable aspect of this symbiosis is that many of the fish that visit the cleaner gobies' cleaning station would otherwise treat such small fish as food (for example groupers and snappers).
See also
- List of fish common names
- List of fish families
- Dragonet (a similar family often confused with gobies)
External link
- Themudskipper.org: a website on mudskippers by G. Polgar (in English)
- FishBase entry on Gobiidae
- Gobioid Research Institute
- Takahiko Mukai's Encyclopaedia of Goby (mostly Japanese)
- Richard Mleczko's Mudskipper & Goby Page
- Article on cleaner gobies in aquaria
- Brackish Water Aquarium FAQ entry on gobies