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Sea of Cortez 810

Family Kyphosidae
Sea chubs, nibblers, and halfmoons
Class: Actinopterygii (ray-finned)
Order: Perciformes

Key Features:
The family Kyphosidae is relatively small and is comprised of only about 42 species in 42 genera.  Most are highly generalized omnivorous grazers, feeding on algae, and both planktonic and benthic invertebrates.  They are very perciform in appearance with an oval body, small mouth and a forked or notched tail, although the tails in halfmoons is distinctly lunate. 

Notable Species in the Sea of Cortez

Girella simplicidens
Gulf Opaleye
Kyphosus analogus
Blue-Bronze Sea Chub
Kyphosus elegans
Cortez Chub
Hermosilla azurea
Zebra-Perch Sea Chub

Kyphosus analogus photographed scuba diving La Paz, Baja, Mexico sea of Cortez

Kyphosus analogus
Blue-Bronze Sea Chub

La Paz, Baja California Sur, Mexico

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San Carlos Scuba Diving

Family Kyphosidae
Sea chubs, nibblers, and halfmoons (Chopas)

Closely related to the freshwater perches, chubs and other kyphosids are similarly perciform.  They are oval-shaped with blunt terminal mouths and notched or forked tails.  They are broadly distributed both within the Gulf and globally due in large part to their generally non-specific feeding requirements.  They are omnivorous, but algae provide the bulk of the diet in many species. 

There are seven species of kyphosids in the Sea of Cortez.  One of the most commonly encountered by scuba divers is a species endemic to the region, the Gulf opaleye, Girella simplicidens.  Their oval body is similar to many other chubs but they may be identified by the presence of three distinct light marks along the dorsal arch above the lateral line. 

A similarly shaped chub is the blue-bronze sea chub, Kyphosus analogus, which is often more abundant in the southern Gulf.  The scales of this fish take on a metallic sheen that is not present in the Gulf opaleye.  The habitat of sea chubs is highly varied, although most are reef grazers picking at both algae and small invertebrates.  One subfamily, Kyphosinaae, also known as the rudderfishes, exists more often in the pelagic environment. These odd fishes derive their name from their habit of chasing boats and snapping up the crustaceans that are attracted to these temporary reefs. 


Updated August 28, 2009

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