From the Smithsonian Institute,
United States National Museum,
Washington DC:

The Men of the U.S.S. Tiru

Gentlemen:

The TIRU is a member of the family Synodontidae, or lizard fishes, which are mostly inhabitants of shore waters in warm seas, some of them descending to considerable depths.

Known scientifically as Synodus saurus (pronounced Si-no-dus sar-us), the TIRU is a long, slender, and rounded like a submarine. The mouth is very wide and each jaw is provided with compressed, knife-sharp teeth, the inner and larger ones depressable; there are also sharp teeth on the bones of the roof of the mouth and on the tongue so that the TIRU is well equipped for purposes of offense and defense. The dorsal (back) fin is slightly higher than long and is followed at a distance by a small fleshy fin called the adipose fin. The caudal (tail) fin is broadly forked, the anal fin is moderately long but not very high, the pelvic (belly) fins are long and the pectoral (breast) fins are short. The eye is far forward on the head so that the snout is very short.

In coloration the TIRU is brownish or grayish above, yellow below, the back finely spotted and vermiculited with black and with eight rather indefinite darker cross-bands. Usually there is a yellow longitudinal band margined with black along the region of the lateral line (on the mid-side). The dorsal fin and the basal parts of the pectoral fins often have small black or brown spots, whereas the caudal fin is dusky, and the anal and pelvic fins are yellow.

Although the TIRU reaches a length of only about 18 inches it is a voracious, carnivorous fish, and the barred and mottled pattern of the back tends to render it inconspicuous against the sandy background over which it lives.

Synodus saurus is found in the Mediterranean Ocean and neighboring parts of the Atlantic as well as in the Bermudas and Leeward Islands of the West Indies.