Gobiidae orgobies is afamily ofbony fish in theorderGobiiformes, one of the largest fish families comprising more than 2,000species in more than 200genera.[1] Most of gobiid fish are relatively small, typically less than 10 cm (3.9 in) in length, and the family includes some of the smallestvertebrates in the world, such asTrimmatom nanus andPandaka pygmaea,Trimmatom nanus are under 1 cm (3⁄8 in) long when fully grown, thenPandaka pygmaea standard length are 9 mm (0.35 in), maximum known standard length are 11 mm (0.43 in). Some large gobies can reach over 30 cm (0.98 ft) in length, but that is exceptional. Generally, they arebenthic or bottom-dwellers. Although few are important asfood fish for humans, they are of great significance asprey species for other commercially important fish such ascod,haddock,sea bass andflatfish. Several gobiids are also of interest asaquarium fish, such as thedartfish of the genusPtereleotris.Phylogenetic relationships of gobiids have been studied using molecular data.[2][3]
The most distinctive aspects of gobiidmorphology are the fusedpelvic fins that form a disc-shaped sucker. This sucker is functionally analogous to thedorsal fin sucker possessed by theremoras or the pelvic fin sucker of thelumpsuckers, but is anatomically distinct; these similarities are the product ofconvergent evolution. The species in this family can often be seen using the sucker to adhere to rocks andcorals, and inaquariums they will stick to glass walls of the tank, as well.
Gobiidae are spread all over the world in tropical and temperate near shore-marine,brackish, and freshwater environments. Their range extends from theOld World coral reefs to the seas of theNew World, and includes the rivers and near-shore habitats of Europe and Asia.[4] Gobies are generally bottom-dwellers. Although many live in burrows, a few species (e.g. in the genusGlossogobius) are truecavefish.[5] On coral reefs, species of gobiids constitute 35% of the total number of fishes and 20% of the species diversity.[6]
Members of Benthophilinae are endemic to the Ponto-Caspian region (including theMarmara,Black,Azov,Caspian, andAral Seas).[8] The representatives of the subfamily have fused pelvic fins and elongated dorsal and anal fins.[9] They are distinguished from the closely related subfamily Gobiinae by the absence of aswimbladder in adults and location of the uppermost rays of thepectoral fins within thefin membrane.[10] Its members includetadpole gobies,monkey gobies, andbighead gobies.
Members of the Gobiinae are known astrue gobies. It is the most widespread and most diverse of the subfamilies formerly recognised under the Gobiidae, containing around 2000 species and 150 genera.
Most species in the Gobiidae attach their eggs to asubstrate, such as vegetation, coral, or a rock surface. They lay from five to a few thousand eggs, depending on the species. After fertilizing the eggs, the male guards the eggs from predators and keep them free fromdetritus. The male fans the eggs, thereby providing them with oxygen. The female maintains the burrow. The eggs hatch after a few days. The larvae are born transparent, and they develop coloration after spreading to find a suitable habitat. The larvae of manyfreshwater gobiid species are carried downstream to thebrackish waters, or even to the sea. They return to fresh water weeks or months later.[11]
Gobiids in warmer waters reach adulthood in a few months, while gobies in cooler environments reach adulthood in two years. The totallifespan of gobiid varies from one to ten years, again with the species in warmer waters generally living longer.[11]
Many species in the Gobiidae live in male-female pairs that construct and share burrows, similar to many other fish such asMozambique tilapia. The burrows are used for shelters andspawning places. Gobiids use their mouths to dig into the sea bottom, removing dead coral-fragments, rubble, andbenthicalgae in order to build their burrows.[12] Gobiids maintain their burrows by fanning away sand inside the burrows. Furthermore, gobies use coral rubble to block burrow entrance. A single goby carry as many as nine pieces of coral rubble per minute. Gobiids also build a 6–13 cm highmound over the entrance of their spawning burrow.[12] The mound lets the water flow fast over the mound. The water flow created by the mound helps to provide oxygen to the eggs. While burrow building is a cooperative behavior done by both sexes, males usually put more effort in burrow maintenance than females. Females feed more instead, because thereproductive success is optimal when females put more energy in preparing for the reproduction.[13] After spawning eggs, the roles of male and female changes. Females primarily maintain the burrow, and males mainly care for the eggs by fanning them, thereby providing oxygen. When females leave the burrow, however, the mounds lose their heights. The males then give up on the eggs and eat them, preparing for future mating opportunities. Gobiid burrows vary in size depending on the size of the species.[13]
Kleptogamy refers to a "sneaking behavior" duringreproduction where an unpaired male fertilises the eggs of a paired female and the paired male cares for the eggs. Females prefer male gobies with large bodies. Since not all males have large bodies, the smaller ones may cheat instead of expending energy to find mates.[14] The sneakers wait near the spawning ground of paired fish. The sneakers then release theirsperm on the spawning ground as soon as the paired female releases hereggs.[15] Though sneakers’ sperm fertilizes some eggs, the paired male cannot distinguish the eggs fertilized by the sneakers from those fertilized by his own sperm. Therefore, the paired male givesparental care equally to all the eggs.[16]
Kleptogamy is a good strategy in many ways. First, the sneakers do not need their own territories, indicating that they do not need to spend energy in protecting territories, as most other males do. Most male gobies need their own territories, since females do not choose to mate with a male that does not own his own territory.[14] Secondly, the sneakers do not provide parental care to their eggs. The paired males provide parental care instead of the sneakers. Therefore, the sneakers can save energy, and they can put more effort into finding new targets for cheating.[14]
The cost of kleptogamy is that the sneakers can receive aggressive attacks from the paired males that are usually much larger and stronger than the sneakers. For small sneakers, the attacks by the paired males can be detrimental and often lead to death.[14]
The sneakers are also referred to as pseudo-females, since they are small and hardly distinguishable from females. This small body size makes cheating easier. Most of the time the paired males mistake the sneakers for females and thus do not chase the sneakers away. The paired males are called "bourgeois" males, because they are larger, stronger, and most importantly, paired.[14]
A 1865 watercolor painting of a Brazilian goby by Jacques Burkhardt
A few species of gobiid, such asblackeye goby andLythrypnus dalli, can change their sexes. Sex change is possible in these gobies, since theexternal genitalia for males and females do not differ much.[14] Sex changes can take from days to weeks. Most sex changes in gobies are from female to male (protogyny) rather than male to female (protandry). Female-to-male changes are observed not only in gobiids but also inwrasses,damselfishes, and seabasses.[14] Female-to-male change usually occurs because the resident male of the group is dead. If no male is in the group,reproduction will be impossible. Therefore, the dominant female turns into male, allowing mating to happen.[17] Male-to-female change occurs when the females have preference for specific features in males. For example, females prefer large males, and a few large males mate with multiple females, whereas small males lose their chance to mate. Small males either choose to become sneakers (kleptogamy) or choose to transform into females because all females technically have high mating opportunities. By turning into females, males can ensure that they produce manyoffspring.[14][18]
Some gobies have extraordinarily developed sex change ability.Gobiodon histrio from theGreat Barrier Reef exhibits bidirectional sex changes.G. histrio is one of the very few species that can change sex in both ways. When twoG. historio females, which used to be males, are on the same coral reef, one of them transforms back into a male goby.[18]
Sex determination in coral gobyGobiodon erythrospilus does not occur until the juveniles meet potential mates.[14] Confronting a potential mate can be difficult forGobiodon erythrospilus juveniles, since most coral resources, crucial for attracting mates, are occupied by pre-existing paired gobies. Juveniles can only meet potential mates when one member of the pre-existing pairs dies. Juveniles’ sexes are determined according to the sexes of their potential mates. When a juvenile meets a female, it becomes a male, andvice versa. This type of sex determination is referred to as socially influenced sex determination.[19]
Some gobiids rememberlandmarks that are within short distances, and use them to find their ways. Small frillfin gobies (Bathygobius soporator) live inintertidal zones. They swim through the pools duringhigh tides and memorize how each pool connects to the others. Then, duringlow tides, they can exhibit accurate jumping behaviors, as they have memorized the paths.[20] In a new environment, these fish do not show jumping behaviors or jump into wrong pools. Nevertheless, after one night, they show the same accurate jumping behaviors.[21]
A study was done to understand how gobiids react to changing habitat. The fish were given two choices: a safe habitat with less food and a dangerous habitat with more food. Results from both the full and hungry fish revealed that gobiids, when confronted with the trade-off betweenforaging and avoidingpredation, made choices that would better their foraging.[22]
Species in the Gobiidae sometimes formsymbiotic relationships with other species,[23] such as with burrowingshrimps. The shrimp maintains a burrow in the sand in which both the shrimp and the fish live. The shrimp has poor eyesight compared to the gobiid, but if it sees or feels the fish suddenly swim into the burrow, it will follow. The fish and shrimp keep in contact with each other, the shrimp using its antennae, and the fish flicking the shrimp with its tail when alarmed. These gobiids are thus sometimes known as "watchmen gobies" or "prawn gobies". Each party gains from this relationship: the shrimp gets a warning of approaching danger, and the fish gets a safe home and a place to lay itseggs. Only thealpha male and female reproduce; other fish in the colony eat sparingly to resist being eaten by the alpha male or female. This way, only the largest and fittest are able to reproduce.[citation needed]
Another example ofsymbiosis is demonstrated by the neon gobies (Elacatinus spp.). These gobiids, known as "cleaner gobies", removeparasites from the skin, fins, mouth, and gills of a wide variety of large fish. The most remarkable aspect of this symbiosis is many of the fish that visit the cleaner gobies'cleaning stations would otherwise treat such small fish as food (for example,groupers andsnapper). Again, this is a relationship where both parties gain: the gobies get a continual supply of food as bigger fish visit their cleaning stations, and the bigger fish leave the cleaning stations healthier than they were when they arrived.
Another form ofsymbiosis exists between gobiids and the mushroom coralHeliofungia actiniformis (Fungiidae), in which representatives of the genusEviota roam among the tentacles possibly hiding from predators.[24][25]
Several species of gobiids are kept in aquaria.[26] Most captive gobies are marine. Perhaps the most popular is the small but colorfulneon goby. Most gobies stay toward the lower portion of the aquarium, hiding in the rockwork, but some species (most notably the shrimp gobies) prefer to dig themselves little burrows. Aquarists typically provide them with a fine-grained substrate to prevent damage to their delicate undersides.Commonly kept saltwater species includeRandall's shrimp goby and thewatchman goby.
Sleeper gobies are a closely related family (Eleotridae) that lack the fused pelvic fin sucker typical of most gobies, but are otherwise very similar in size, shape, and ecology.
Blennies are a group of shallow-water marine fish often confused with gobies.
Dragonets are superficially similar to gobies and sometimes confused with them.
^Patzner, R.A.; Van Tassell, J.L.; Kovačić, M.; Kapoor, B.G., eds. (2011).The Biology of Gobies. Enfield, NH: Science Publishers. p. 685.ISBN978-1-57808-436-4.
^Agorreta, A.; San Mauro, D.; Schliewen, U.; Van Tassell, J.L.; Kovačić, M.; Zardoya, R.; Rüber, L. (2013). "Molecular phylogenetics of Gobioidei and phylogenetic placement of European gobies".Molecular Phylogenetics and Evolution.69 (3):619–633.Bibcode:2013MolPE..69..619A.doi:10.1016/j.ympev.2013.07.017.hdl:10261/123985.PMID23911892.
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^Winterbottom, Richard; et al. (2011). "Life span, growth and mortality in the western Pacific goby Trimma benjamini, and comparisons with T. nasa".Environmental Biology of Fishes.91 (3):295–301.Bibcode:2011EnvBF..91..295W.doi:10.1007/s10641-011-9782-6.
^abHoese, Douglas F. (1998). Paxton, J.R.; Eschmeyer, W.N. (eds.).Encyclopedia of Fishes. San Diego: Academic Press. pp. 218–222.ISBN978-0-12-547665-2.
^abTakegaki, Takeshi; Akinobu Nakazono (June 1999). "Division of labor in the monogamous goby, Valenciennea longipinnis, in relation to burrowing behavior".Ichthyological Research.46 (2):125–129.Bibcode:1999IchtR..46..125T.doi:10.1007/BF02675430.
^Svensson, O; Magnhagen, C.; Forsgren, E.; Kvarnemo, C. (1998). "Parental behaviour in relation to the occurrence of sneaking in the common goby".Animal Behaviour.56 (1):175–179.doi:10.1006/anbe.1998.0769.PMID9710475.S2CID24806138.
^Lorenzi, V.; Earley, R.L.; Grober, M.S. (2006). "Preventing behavioural interactions with a male facilitates sex change in female bluebanded gobies, Lythrypnus dalli".Behavioral Ecology and Sociobiology.59 (6):715–722.doi:10.1007/s00265-005-0101-0.
^abMunday, P.L.; Caley, M.J.; Jones, G.P. (1998). "Bi-directional sex change in a coral-dwelling goby".Behavioral Ecology and Sociobiology.43 (6):371–377.doi:10.1007/s002650050504.
^Bos AR, Hoeksema BW (2015). "Cryptobenthic fishes and co-inhabiting shrimps associated with the mushroom coral Heliofungia actiniformis (Fungiidae) in the Davao Gulf, Philippines".Environmental Biology of Fishes.98 (6):1479–1489.Bibcode:2015EnvBF..98.1479B.doi:10.1007/s10641-014-0374-0.
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