Morphology Data of Gasterosteus aculeatus
Identification keys
Abnormalities
Main Ref. Banister, K., 1986
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs no special organs
Different appearance males alike females
Different colors males alike females
Remarks

Descriptive characteristics of juvenile and adult

Striking features
Body shape lateral fusiform / normal
Cross section
Dorsal head profile more or less straight
Type of eyes more or less normal
Type of mouth/snout more or less normal
Position of mouth terminal
Type of scales
Diagnosis

Distinguished uniquely from its congeners in Europe by having trunk and caudal peduncle covered by a complete series of 29-35 bony scutes. Other characters important to separate this species from other species of the genus include posterior edge of scutes crenulated and scutes forming a lateral keel on caudal peduncle. Scutes may be missing on posterior part of trunk in hybrid zone with Gasterosteus gymnurus and in some isolated freshwater populations of northeastern Europe (Ref. 59043). Identified by the 3 to 4 sharp, free spines before the dorsal fin, the pelvic fin reduced to a sharp spine and a small ray, and the series of plates along the sides of the body (Ref. 27547). Gill rakers long and slender, 17 to 25 on the first arch or strictly freshwater forms, 1 or 2 more in anadromous forms; lateral line with microscopic pores (Ref. 27547). The anadromous form is fully plated, with up to 37 plates on the sides and a rather pronounced keel on each side of the caudal peduncle (Ref. 27547). Dorsal spines separated from each other and from the soft-rayed fins, each spine having a reduced membrane attached to its posterior side; anal spine free from rest of the fin; posterior margin of pectorals nearly truncate; caudal truncate to slightly indented (Ref. 27547). Freshwater forms usually mottled brown or greenish; anadromous forms silvery green to bluish black (Ref. 27547). A few isolated populations are black (Ref. 27547). Sides usually pale; belly yellow, white or silvery (Ref. 27547). Fins pale; pectoral rays often have dark dots (Ref. 27547). Breeding males (except for black forms) become brilliant bluish or green with blue or green eyes, and the forward part of the body, especially the breast region, turns bright red or orange (Ref. 27547). Caudal fin with 12 rays (Ref. 2196).

Ease of Identification

Meristic characteristics of Gasterosteus aculeatus

Lateral Lines 1 Interrupted: No
Scales on lateral line
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle
Barbels 0
Gill clefts (sharks/rays only) absent
Gill rakers
on lower limb
on upper limb
total
Vertebrae
preanal
total 29 - 34

Fins

Dorsal fin(s)

Attributes other
Fins number 2
Finlets No. Dorsal   0 - 0
Ventral  0 - 0
Spines total 2 - 4
Soft-rays total 10 - 14
Adipose fin absent

Caudal fin

Attributes more or less truncate; more or less normal

Anal fin(s)

Fins number 1
Spines total 1 - 1
Soft-rays total 7 - 11

Paired fins

Pectoral Attributes  more or less normal
Spines     0
Soft-rays   10 - 10
Pelvics Attributes  more or less normal
Position    thoracic  before origin of D1
Spines     1
Soft-rays   1 - 1
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Entered by Luna, Susan M.
Modified by Torres, Armi G.
Checked by Pauly, Daniel
Comments & Corrections
Sign our Guest Book
Back to Search
cfm script by eagbayani, 17.10.00, php script by rolavides, 13/03/08 ,  last modified by sortiz, 06.27.17