Trachinoids are mostly benthic, questionably related marinefishes, several of which sit buried in the sand throughout the day or seek refuge in the sand when not feeding. Chiasmodontid swallowers depart from the suborder normin being one of the few acanthopterygians to occupy mesopelagicand bathypelagic depths. They show convergenttraits with other deepsea fishes, including a large mouth,long teeth, slender jaw bone elements, distensible mouthand stomach, black coloration, and photophores. TheCheimarrichthyidae consist of a single New Zealand species, Cheimarrichthys fosteri. It is known as the Torrent fish,reflecting its daytime habitat in turbulent streams. Its body form, inferior mouth, large horizontally placed pelvics, and broad flattened head converge with other swift waterfishes such as Longnose Dace, balitorine hillstream loaches,African kneriids, amphiliid loach catfishes, clingfishes, andrhyacichthyid loach gobies (see Strongcurrentsand turbulent waters). Trichonotid sanddivers share apeculiarity with some elasmobranch rays by having rotuberanteyes and a dorsal eyelid of sorts made up of an irisfl ap with strands that extend over the lens. Both groups rest on or bury in the sand in shallow water with only their eyesvisible.
Ammodytid sand lances are small, elongate, shoalingfishes that feed on zooplankton in the water column by dayand spend nighttime buried in the sand. The trachinid weeverfishes are well-known eastern Atlantic and Mediterraneanbenthic fishes with highly venomous opercular anddorsal spines. The uranoscopid stargazers are another venomousfamily, with two grooved spines and an accompanyinggland sitting just behind the gill cover and above thepectoral fins. Stargazers also lie on the bottom or bury in the sand, with their dorsally located eyes exposed. Their incurrent nostrils are directly connected to the mouth,which may allow them to breathe while buried. A fleshyfilament extends upward from the floor of the mouth andis used to lure prey. Stargazers include some of the onlymarine teleosts that are electrogenic, strong pulses of electricity(up to 50 volts) being produced by highly modified extrinsic eye muscles. They discharge when captured and may also use electricity to stun prey. Stargazers are convergentin body form and habits with paracanthopterygiantoadfishes and blennioid dactyloscopid sand stargazers.
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