Key to Identification of Aquatic Vertebrates

VERTEBRATES  Aside from fishes and birds, there are only a few vetebrates associated with aquatic environments in the Hawaiian Islands: five species of amphibians and three species of turtles; all eight are introduced or exotic species. Rats sometimes frequent riparian forests. For the most part, the vertebrates are well-known and described in various scientific papers and popular handbooks. Only the fishes present much difficulty from a taxonomic perspective because of numerous introduced species, mostly from the tropical fish aquarium trade, whose native origins may be obscure. A list of vertebrate species (presently excluding birds and mammals) associated with aquatic environments in Hawai`i is provided elsewhere in CPIE.

	25a	(10)	Lacking legs or limbs, other than fins. Free-swimming, although may rest on or burrow into bottom. Aquatic, breathing by gills	[26]
	25b		Organism has limbs: legs or wings; free-swimming, crawling, burrowing, or flying. Semi-aquatic or terrestrial, breathing by lungs	[27]
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	26a	(25)	Swimming usually strong, propelled by sets of fins on body. Shape typically streamlined (fusiform or nearly so). Fishes	[33]
	26b		Swimming weak by means of a long, flattened tail; no fins present on a bulbous (more or less rounded) body. Hind leg rudiments (buds) may be present. Frog or toad tadpole	[37]
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	27a	(25)	Outer covering of feathers. Front limbs are wings, used for flying. Birds	[63]
	27b		Front and hind limbs similar (four-legged). Swimming, walking, or jumping, but not capable of flying	[28]
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	28a	(27)	Body covering skin and/or with scales, but without hair	[29]
	28b		Body covering mostly hair (fur) ~ MAMMALIA	[53]
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	29a	(28)	Animal has a hard outer covering (shell) into which the head, legs, and tail can be withdrawn for protection. Lakes, reservoirs, rivers, and canals, maybe in streams near lakes. Turtles ~ REPTILIA	[30]
	29b		Animal lacking a shell. Skin without scales. Frogs and toads ~ AMPHIBIA	[32]

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REPTILIA  [CPIE Hawaiian Reptilia List]  Although native lizards and sea turtles occur in Hawai`i, no native aquatic reptiles are known, no doubt because of the difficulty vertebrates from freshwater habitats would have crossing the vast Pacific Ocean. Three species of freshwater turtles have been introduced (McKeown, 1996) and may be observed around streams and ponds on O`ahu and Kaua`i. Turtles are semiaquatic and lay their eggs on land close to the water. Upon hatching, the juvenile turtle seeks suitable habitat, usually a pond or lake. Sizes of adults are given in the key as the shell length in centimeters.

	30a	(29)	Shell hard and covered with horn-like plates; carapace (upper portion) marked in brown and black streaks (green in juveniles); sawtooth posterior margin. Nose blunt; red stripe on head behind eye and above yellow stripes down from eye and mouth. Grows to 25 cm. Red-eared slider ~ Family EMYDIDAE Trachemys scripta elegans (Wied)
	30b		Shell pliable, covered with a smooth, leathery skin. Nose elongate, snorkle-like. Soft-shell turtles ~ Family TRIONYCHIDAE	[31]
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	31a	(30)	Front margin of shell a ridge divided into tubercles. Juveniles (under 1 year old) with yellow markings on neck. To 40 cm. Wattle-necked softshell Palea steindachneri
	31b		Front margin of shell mostly a smooth ridge. Head with white and black-ringed spots. Juveniles lack yellow neck markings. Chinese softshell Pelodiscus sinensus (Wiegmann)