Stargazer (fish)

The stargazers are a family, Uranoscopidae, of perciform fish that have eyes on top of their heads (hence the name). The family includes about 51 species (one extinct) in eight genera, all marine and found worldwide in shallow and deep saltwaters.[1]

Stargazer
Common stargazer, Kathetostoma laeve
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Trachiniformes
Family: Uranoscopidae
Jordan & Evermann, 1898
Genera

See text

Description

In addition to the top-mounted eyes, a stargazer also has a large, upward-facing mouth in a large head. Their usual habit is to bury themselves in sand, and leap upwards to ambush prey (benthic fish and invertebrates) that pass overhead. Some species have a worm-shaped lure growing out of the floors of their mouths, which they can wiggle to attract prey's attention. Both the dorsal and anal fins are relatively long; some lack dorsal spines. Lengths range from 18 up to 90 cm, for the giant stargazer Kathetostoma giganteum.

Stargazers are venomous; they have two large venomous spines situated behind their opercles and above their pectoral fins. The species within the genera Astroscopus and Uranoscopus can also cause electric shocks. Astroscopus species have a single electric organ consisting of modified eye muscles, while Uranoscopus species have theirs derived from sonic muscles.[2] These two genera within stargazers represent one of eight independent evolutions of bioelectrogenesis.[2] They are unique among electric fish in not possessing electroreceptors, meaning that they do not use an electric sense to locate prey.[2]

Stargazer's paired electric organs are aligned vertically inside the head, behind the eyes.[3] Uniquely, they are used only for hunting or defence, as the fish does not electrolocate.[2]

Stargazers are a delicacy in some cultures (the venom is not poisonous when eaten), and they can be found for sale in some fish markets with the electric organ removed. Stargazers are ambush predators which camouflage themselves; some can deliver both venom and electric shocks. Ichthyologist William Leo Smith called them "the meanest things in creation".[4]

Genera

Uranscopidae contains the following genera: [5]

Timeline
QuaternaryNeogenePaleogeneHolocenePleist.MioceneOligoceneEocenePaleoceneAstroscopusQuaternaryNeogenePaleogeneHolocenePleist.MioceneOligoceneEocenePaleocene

References
  1. Bray, Dianne. "Family Uranoscopidae". Fishes of Australia. Retrieved 30 September 2014.
  2. Alves-Gomes, J. A. (2001). "The evolution of electroreception and bioelectrogenesis in teleost fish: a phylogenetic perspective". Journal of Fish Biology. 58 (6): 1489–1511. doi:10.1006/jfbi.2001.1625.
  3. Berry, Frederick H.; Anderson, William W. (1961). "Stargazer fishes from the western north Atlantic (Family Uranoscopidae)" (PDF). Proceedings of the United States National Museum. 1961.
  4. Grady, Denise (22 August 2006). "Venom Runs Thick in Fish Families, Researchers Learn". The New York Times. Archived from the original on 7 December 2013.
  5. Froese, Rainer, and Daniel Pauly, eds. (2022). "Uranscopidae" in FishBase. June 2022 version.

Further reading
External video
video icon Stargazer lunges from sand – YouTube
video icon Little Red Cardinalfish gets eaten by hidden Stargazer! – YouTube
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