Dactyloscopidae
Sand stargazers

Dactyloscopids derive their common name, sand stargazers, from their eyes, which protrude from the tops of their heads, sometimes on stalks. Sand stargazers usually remain burrowed into the sand with only the eyes, along with the snout and sometimes the top of the head, uncovered. Members of this family occupy shallow warm waters and are carnivorous. They are small, cryptic fishes and little is known about their behavior or reproductive habits. There are nine genera in the family and about 41 species. (Böhlke and Chaplin, 1993; Nelson, 1994; Springer, 1998; Wheeler, 1985)

Dactyloscopids, or sand stargazers, are found in tropical and warm temperate waters of the western hemisphere. The Atlantic Ocean (from the United States to Brazil) contains 17 species, and the Pacific Ocean (from the Gulf of California to Chile) contains 24. (Allen and Robertson, 1994; Böhlke and Chaplin, 1993; Nelson, 1994; Springer, 1998; Wheeler, 1985)

Dactyloscopids live buried in the sand with only the eyes, along with the snout and sometimes the top of the head, uncovered. They usually occupy shallow warm water at depths between two and 15 m, but one species, Gillellus semicinctus, has been found between five and 137 m. Some groups inhabit bare, open beaches in or behind the surge zone, but others are found exclusively in patches of sand that are near rocks, coral structures, or marl bottoms. A few species can be found in estuaries, and at least one enters fresh water. (Allen and Robertson, 1994; Böhlke and Chaplin, 1993; Wheeler, 1985)

Sand stargazers (family Dactyloscopidae) are small fishes adapted to burrowing in the sand. Their eyes are situated on the top of the head, sometimes on stalks, and their nostrils are tubular. They have upturned mouths, and fingerlike projections (fimbriae) line the mouth and gill covers, keeping sand out of the gills and mouth. These fish maintain water flow through the gills with a branchiostegal pump. Sand stargazers are covered with cycloid scales. The dorsal fin, which contains 7-23 spines and 12-36 soft rays, may be divided or continuous. The pelvic fins have three thickened rays with tips that are free from the fin membrane. The largest dactyloscopids reach 17 cm, but most are less than six cm. They are colored to blend in with their sandy environment: most are whitish or drab brown, and many have red-tinged or dark mottling along the back and head. (Click here to see a fish diagram) (Allen and Robertson, 1994; Böhlke and Chaplin, 1993; Nelson, 1994; Springer, 1998; Wheeler, 1985)

No information was found on development in Dactyloscopidae.

No information was found on mating systems in Dactyloscopidae.

While no information was found on reproduction in Dactyloscopidae, blennies (which are in the same suborder Blennioidei) in general tend to lay relatively large eggs that adhere to a surface. In the case of sand stargazers, eggs may adhere to each other, as males carry them in two clumps under the pectoral fins. (Thresher, 1984)

Sand stargazers display a unique trait among fishes in that males guard eggs by carrying them in two balls, one in the “armpit” (axilla) of each pectoral fin. (Allen and Robertson, 1994; Böhlke and Chaplin, 1993; Helfman, et al., 1997; Wheeler, 1985)

No information was found on lifespan of dactyloscopids.

Sand stargazers burrow in the sand and remain there most of the time lying in wait for their prey. They delve into the sand using sinuous body and anal fin motions, and swimming movements of the pectoral fins. They may bury themselves completely or leave the eyes, snout or top of the head uncovered. One behavior engaged in by males is egg-guarding, accomplished by carrying a ball of eggs under each pectoral fin. (Allen and Robertson, 1994; Böhlke and Chaplin, 1993; Springer, 1998; Wheeler, 1985)

No information was found on communication in Dactyloscopidae. Because their eyes are placed on top of their heads, often on stalks, so as to remain uncovered by sand, it is logical to infer that they perceive their surroundings visually.

Sand stargazers are carnivorous, lying in wait under the sand to attack small fishes and invertebrates. (Allen and Robertson, 1994; Wheeler, 1985)

Sand stargazers conceal themselves from predators by hiding under the sand. They are cryptically colored, so any exposed parts blend in well with the sand. (Böhlke and Chaplin, 1993; Springer, 1998; Wheeler, 1985)

Sand stargazers occupy a specific habitat, that is, sandy bottoms of shallow warm waters, and in that setting impact the tiny fishes and invertebrates that serve as their prey. (Allen and Robertson, 1994; Wheeler, 1985)

No information was found on human importance of Dactyloscopidae.

No specific information was found concerning any negative impacts to humans.

There is no known conservation threat to any members of Dactyloscopidae. (The World Conservation Union, 2002)