Morphology Data of Tylosurus acus
Identification keys
Main Ref. Allen, G.R. and M.V. Erdmann, 2012
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance
Different colors

Descriptive characteristics of juvenile and adult

Striking features striking type of mouth
Body shape lateral elongated
Cross section circular
Dorsal head profile more or less straight
Type of eyes more or less normal
Type of mouth/snout other (see Diagnosis)
Position of mouth terminal
Type of scales

Diagnosis: body elongate; upper and lower jaws extremely long, forming a stout beak armed with very sharp teeth; gill rakers absent (Ref. 57228, 90102). Nostrils in depression before eyes (nasal pit); pelvic fins abdominal; 20-26 dorsal-fin rays; anal fin short, 9.7-11.7 times in body length; small, black lateral keel on either sides of caudal peduncle; caudal fin deeply forked (Ref. 57228).

Description: body less rounded in cross-section than T. crocodilus (Ref. 57228). Upper jaw nearly even with lower jaw (Ref. 90102). Anterior rays of dorsal and anal fins forming relatively high lobes that are comprised from 10.5-13.3 and from 9.7-11.7 times, respectively, in body length (Ref. 57228, 90102). Dorsal fin origin about equal with or slightly anterior to origin of anal fin (Ref. 90102). Pectoral and pelvic fins rather short, comprised from 8.0-12.4 and from 10.0-14.1 times, respectively, in body length (Ref. 57228). Lower lobe of caudal fin longer than upper (Ref. 57228, 90102). 267-430 (Ref. 57228) or 280-340 (Ref. 90102) predorsal scales. Left gonad absent or strongly reduced in both sexes (Ref. 57228).

Coloration: back dark blue, belly silvery white; blue line along sides (Ref. 57228). Dorsal fin in juveniles with elevated posterior lobe which disappears with growth (Ref. 57228). Blackish margin on caudal fin (Ref. 90102).

Ease of Identification

Meristic characteristics of Tylosurus acus

Lateral Lines 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)
Gill rakers
on lower limb 0 - 0
on upper limb 0 - 0
total 0 - 0
total 90 - 95


Dorsal fin(s)

Attributes no striking attributes
Fins number 1
Finlets No. Dorsal   
Spines total 0 - 0
Soft-rays total 20 - 27
Adipose fin absent

Caudal fin

Attributes forked; asymmetric

Anal fin(s)

Fins number 1
Spines total 0 - 0
Soft-rays total 20 - 24

Paired fins

Pectoral Attributes  more or less normal
Spines     0
Soft-rays   13 - 14
Pelvics Attributes  more or less normal
Position    abdominal  before origin of D1
Spines     0
Soft-rays   6 - 6
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Comments & Corrections
Back to Search
cfm script by eagbayani, 17.10.00, php script by rolavides, 13/03/08 ,  last modified by sortiz, 06.27.17