CHORDATE ZOOLOGY: STUDY GUIDE - Zakharenko M.O. - 2015

1 (2)

Jaws absent. Mouth in the form of a sucker. Branchial Skeleton lacking isolated, independent arches. Nasal opening single, located anterior to the eyes. There are 7 gill openings on each side of the body.

Lamprey family - Petromyzontidae (8 genera).

2(1)

Jaws present. Mouth not in the form of a sucker. Branchial skeleton possesses distinct, isolated gill arches. Nasal openings usually paired.

3 (12)

Five pairs of gill slits. Opercula (gill covers) absent.

4 (9)

Gill slits located on the sides of the HEAD. Body fusiform (spindle-shaped).

5(8)

Anal fin present.

6 (7)

Two dorsal fins of equal size. Lateral keels on the caudal peduncle absent. Gill slits small. Nictitating membrane present.

1. First dorsal fin is located behind the vertical line of the pelvic fin bases. Catshark family - Scyliorhinidae (16 genera).

2. First dorsal fin is located in front of the vertical line of the pelvic fin bases. Upper lobe of the caudal fin larger than the lower. Requiem shark family - Carcharhinidae (12 genera).

7(6)

Two dorsal fins of unequal size. The first fin is significantly larger and situated anterior to the vertical line of the pelvic fin bases. Well-developed keels present on the caudal peduncle. Gill slits large. Mackerel shark family - Lamnidae (3 genera).

8 (5)

Anal fin absent. 1. Both the First and Second dorsal fins bear a spine. Dogfish shark family - Squalidae (2 genera).

2. Spines absent in the dorsal fins. Sleeper shark family - Somniosidae (7 genera).

9 (4)

Gill slits located on the ventral side of the body. Body flattened dorsoventrally.

10 (11)

Two small dorsal fins present on the tail. Serrated spine on the tail absent. Body usually covered with small denticles. Skate family - Rajidae (26 genera).

11 (10)

Dorsal fins absent on the tail, but a serrated spine is present. Body naked. Stingray family - Dasyatidae (6 genera).

12 (3)

One pair of gill slits. Opercula present (poorly developed in eels, peg-leg Fishes, and pipefishes).

13

(166)

Body symmetrical. Eyes located on the sides of the head or dorsally.

14

Pelvic fins present. Sometimes modified into a bifurcated barbel shifted to the chin, a sucking disc, or spines.

(151)

15 (16)

Body with five rows of bony scutes (plates). Mouth located on the ventral side of the head as a transverse slit. Upper lobe of the caudal fin significantly longer than the lower, bearing small rhombic (ganoid) scales and fulcra. Sturgeon family - Acipenseridae (4 genera).

16 (15)

Body lacking five rows of bony scutes (covered with scales, bony plates, or naked). Mouth not a transverse slit (in nases, khramulias, and golden-fins from the cyprinid family, the mouth is inferior and transverse). Upper lobe of the caudal fin not longer than the lower; rhombic ganoid scales and fulcra absent.

17

(150)

Pelvic fins not modified into spines. Free spines lacking in front of the dorsal fin.

18

(149)

Lateral line single-rowed or absent. Two nostrils (anterior and posterior) on each side of the snout.

19

(146)

Lips framing the mouth neither broad nor thick, and not protruding forward (in the genus Hemibarbus of the cyprinid family, the lips are thick and barbel-less).

20 (69)

Pelvic fins located on the abdomen or noticeably behind the Base of the pectoral fins; occasionally, THE ORIGIN OF their base lies beneath the end of the pectoral fins.

21 (64)

Single dorsal fin, consisting of soft branched rays. Sometimes preceded by a smooth or serrated spine. In addition to the dorsal fin, an adipose fin lacking ray Supports may occasionally be present on the back.

22 (59)

Gill membranes usually not attached to the interbranchial space (exceptionally, in bagrid catfishes - Bagridae, sisorid catfishes - Sisoridae, and North American freshwater catfishes - Ictaluridae, the gill membranes are fused to a greater or lesser extent with the interbranchial space at their posterior ends, and an adipose fin is always present). Mouth not protrusible, usually armed with weak or strong Teeth.

23 (44)

Adipose fin absent.

24 (43)

Anal fin of moderate length, with no more than 30 rays; dorsal fin with more than 5 rays.

25 (28)

Dorsal fin situated above the pelvic fins or slightly anterior or posterior to the vertical of their base. Lateral line absent. Scales deciduous (easily shed).

26 (27)

Mouth terminal or superior, large or small. If the mouth is large, the posterior end of the Maxilla extends past the vertical of the middle of the eye. Abdomen with a well-defined or weak keel. Herring family - Clupeidae (57 genera).

27 (26)

Mouth oblique, inferior, very large. Snout protruding forward. Posterior end of the maxilla extends past the margin of the preoperculum. Keel absent. Anchovy family - Engraulidae (16 genera).

28 (25)

Dorsal fin shifted far backward, positioned above the anal fin. Scales firmly attached. Lateral line present or absent.

29(42)

Lateral line present, located mid-laterally or ventrally (in pike family juveniles, the lateral line is indistinct; moreover, their snout is greatly elongated and the dorsal fin is shifted backward).

30 (35)

Pectoral fins positioned low, usually near the ventral margin of the body. Lateral line running along the middle of the body.

31 (32)

Body elongate, snout elongated. Mouth very large. Caudal fin emarginate. Pike family - Esocidae (1 genus).

32 (31)

Body not elongate and snout not elongated. Mouth small. Caudal fin rounded.

33 (34)

Scales small (more than 70 scales in the lateral line). Anal fin with 14-16 rays, pectoral with 33-37, pelvic with 3 rays. Mudminnow family - Dalliidae (1 genus).

34 (33)

Scales large (no more than 35 scales in the lateral line). Anal fin with 5-6 rays, pectoral with 12-16, pelvic with 6-7 rays. Central mudminnow family - Umbridae (2 genera).

35 (30)

Pectoral fins positioned high (no lower than eye level), while the lateral line is low.

36 (41)

Both jaws extended into a long or short beak, or only one jaw elongated. Mouth armed with small teeth. Pectoral fins short. Lobes of the caudal fin equal.

37 (40)

Small auxiliary finlets absent behind the dorsal and anal fins.

38 (39)

Upper and lower jaws nearly equal in length. Scales small: over 150 scales in the lateral line. Needlefish family - Belonidae (10 genera).

44 (23)

Adipose fin present.

45 (62)

Barbels present.

50 (45)

Barbels absent.

51 (58)

Body covered with scales. Dorsal fin located anterior to the vertical of the pelvic fins or directly above them.

52 (57)

Lateral line complete.

53 (56)

Body scales firmly seated, cycloid. Eyes usually small. Snout length exceeds the vertical eye diameter.

54 (55)

Dorsal fin short, with fewer than 16 rays. Salmon family - Salmonidae (7 genera).

55 (54)

Dorsal fin long, with more than 17 rays. Grayling family - Thymallidae (1 genus).

62 (63)

Barbels absent or numbering no more than two pairs (in the genus Gobiobotia of the cyprinid family - eight-barbeled gudgeons - there are four pairs of barbels; unlike other cyprinids, loaches in this genus have large scales). Swim bladder free, not enclosed in a bony capsule, which can be verified by dissection. Pharyngeal teeth present. Carp family - Cyprinidae (220 genera).

63 (62)

Barbels numbering at least three pairs. Body naked or covered with very minute scales. Swim bladder entirely or partially enclosed in a bony capsule. Pharyngeal teeth absent. Loach family - Cobitidae (26 genera).

64 (21)

Two dorsal fins, separate from each other. The first consists of unbranched or spiny rays, the second of soft rays. Adipose fin completely absent.

65 (68)

Body of moderate length. Snout short. Lower jaw not projecting forward. Mouth armed with weak teeth.

66 (67)

Head not compressed laterally. First dorsal fin with 4 (very rarely 3 or 5) spiny rays, second with 8-9 branched rays; anal fin with 2-3 unbranched and 7-12 (usually 8-9) branched rays. 6-7 brown stripes along the body sides. Mullet family - Mugilidae (17 genera).

67 (66)

Head compressed laterally. First dorsal fin with 3-8 flexible unbranched rays, second with 1-2 unbranched and remaining branched rays. Anal fin with 1 flexible unbranched ray and 13-15 branched rays. A silvery stripe runs along the sides of the body (brown stripes absent). Silverside family - Atherinidae (12 genera).

78 (83)

Pelvic fins fused together, forming a sucking funnel or disc.

79 (80)

Pelvic fins form a sucking funnel with clearly distinct rays. Goby family - Gobiidae (210 genera).

80 (79)

Pelvic fins form a sucking disc with a membranous border, rays not visible within it.

165

(164)

Mouth terminal. Jaws armed with small comb-like or bristle-like teeth. Body eel-like. Long dorsal and anal fins confluent with the caudal fin. Body not terminating in a slender filament. Freshwater eel family - Anguillidae (1 genus).

166 (13)

Body asymmetrical. Both eyes on the same side of the head.

167(168)

Body deep, body depth exceeding 50% of the total length. Small spinules usually present on the body. Pelvic fins asymmetrical: on the eyed side, they are located at the very margin of the body, while on the blind side, they are set slightly back from the margin. Turbot family - Bothidae (20 genera).

168

Body not deep, body depth less than 50% of the total length. Body

(167)

lacking large spinules. Pelvic fins symmetrical.

169

(170)

Mouth terminal or subterminal. Body shape oval. Righteye flounder family - Pleuronectidae (23 genera).

170

(169)

Mouth inferior (upper jaw visible). Body Tongue-shaped. Sole family - Soleidae (35 genera).

FAMILY ESOCIDAE - PIKES

Body elongate and low. Head large with a strongly elongated and flattened snout. Mouth very large. Dorsal fin positioned above the anal fin; strong teeth present on the premaxillae, Vomer, tongue, and dentaries. Cheeks scaled. Genus of pikes - Esox (5 species).

FAMILY SILURIDAE - SHEATFISHES

Body naked. Adipose fin absent. Anal fin long, with at least 70 rays. Dorsal fin with no more than 5 rays. Head and mouth large. Barbels present. Jaws equipped with numerous brush-like teeth. Three pairs of barbels. Genus of catfishes - Silurus (2 species).

FAMILY THYMALLIDAE - GRAYLINGS

Body covered with tightly adherent cycloid scales. Lateral line complete. Adipose fin present. Dorsal fin long, with at least 17 rays. Mouth small. Teeth on the jaws weak. Genus of graylings - Thymallus (4 species).

FAMILY COBITIDAE - LOACHES

Mouth protrusible, toothless. Teeth present only on the lower pharyngeal bones. Body naked or covered with minute scales. Adipose fin absent. Pelvic fins located posterior to the pectorals. At least three pairs of barbels. Swim bladder connected to the gut; entirely or partially enclosed in a bony capsule.

6 or 8 barbels.

A bifurcated spine present beneath the eye on each side, sometimes deeply hidden under the Skin. Head compressed laterally. Caudal fin rounded. Genus of spined loaches - Cobitis (5 species).

10 barbels, of which 4 are located on the lower jaw. Caudal fin rounded.

Genus of weatherloaches - Misgurnus (8 species).