Sand goby spot at the rear of the first dorsal fin, ringed with white. The fish has a slender body, and the head is about a quarter of the total length. The sand goby has two dorsal fins with a wider gap between them than the common goby ("Pomatoschistus microps"), the anterior one consisting of six soft spines and the posterior one eight to eleven soft rays. The pelvic fins are fused with the anal fins. There are 58 to 72 scales along the lateral line and these scales are rather smaller than those of the common goby. The caudal fin is
Pacific leaping blenny members of "A. arnoldorum" are able to thrive on land due to their ability to twist their tails axially at 90 degrees, to propel their bodies. Hsieh noted that the twisting of the tail was a behaviourism unique to "A. arnoldorum" and species in the genus "Andamia"; the two genera were subsequently considered terrestrial. Pacific leaping blenny The Pacific leaping blenny ("Alticus arnoldorum"), also known as the leaping rockskipper, is a species of combtooth blenny (family Blenniidae) in the genus "Alticus". The blennies are oviparous, and form distinct pairs when mating. Males can reach a maximum total length of 8