Southern Stargazer

The stargazers are a family of fish characterized by eyes on the top of their heads. There are about 50 extant species found worldwide in shallow seas and oceans. The southern stargazer, Astroscopus y-graecum, is our local family member. It’s genus, Astroscopus, is from Latin and means “one who aims at the stars.” This unusual and stout fish has completely adapted to spending most of its life buried in the sand. Its eyes, gill slits, nostrils, and mouth are on the top of its body, so that they are above the substrate while the rest of the fish is underneath. The eyes are capable of protruding for a short distance, appearing stalked, allowing the stargazer peer above the substrate more easily. Water comes in through the nostrils to breathe. (Most fish species bring in water through their mouths.) The nostrils are also protected from loose substrate particles by fleshy, comb-shaped fringes. The gill slit is narrow and drawn backwards and upwards into a baggy tube. The stargazer’s body is blackish-brown and covered with white spots that gradually increase in size towards the tail, which sports three dark, horizontal stripes. Scales are absent on head, but are present on body. They can reach up to 1.5 feet in length. Two largish venomous spines are located behind their ears / above their pectoral fins. And if that’s not enough to deter you from grabbing one, these fish also possess a pair of electric organs behind the eyes, which can emit a shock of up to 50 volts. Stargazers are unique among electric fish in not possessing specialized electroreceptors. Instead, their organs developed from modified eye muscles. Shocks are used primarily to ward off predators, rather than for capturing prey.

The southern stargazer occurs in the western Atlantic Ocean from North Carolina and the northern Gulf of Mexico, south to the northern coast of South America. It is a demersal species that lives most of its life inshore, preferring silty, sandy, or soft-rubble bottoms up to about 300 feet in depth, though usually shallower than 200 feet. Living a largely solitary existence, stargazers can disappear within a matter of seconds by using their pectoral fins like shovels to bury themselves in the substrate. They lie in wait with only their face protruding. As a predatory species, the southern stargazer feeds on smaller fish that have the misfortune of swimming near it. Prey capture does not involve the electrical organ. Instead, the stargazer relies on its camouflage and ambush technique. When a suitable meal passes overhead, the stargazer lunges upwards and instantly sucks it in. They feed primarily on small fish and invertebrates. Flanges on the edges of the stargazer’s upturned mouth prevent the inhalation of sand and may also entice prey by mimicking a tasty treat. (Some stargazer species have an actual lure protruding from the floor of their mouths, but the southern gazer has to suffice with fringy lips.)

True to its benthic nature, the southern gazer spawns on the bottom during the late spring and early summer months. The small, transparent eggs slowly float to the surface, and hatch into equally small, transparent larvae that live in the water column. At this stage, they’re bilateral, with an eye on either side of the head. The pelagic larvae grow rapidly, feeding off the yolk sac until they reach about 6-7mm in length. Then they switch to feeding on other larvae in the water column (including other stargazer larvae). They also begin to darken in color, except for a bright yellow spot that appears on the chin. The electric organs begin to form when the larvae reach about 12-15mm in length, which is also when they move inshore to sandy bays and head for the bottom. Here the larvae become juveniles and develop the characteristic adult patterns. The eyes, which were on the side of the larval head, migrate to the top of the head. When the juveniles reach about a foot in length, they’re considered adults and generally move offshore.

Stargazers are taken as bycatch in seine and bottom trawl fisheries and are especially susceptible to red tide events in Texas bays and nearshore Gulf beaches. If approached by a diver, they generally will not move unless disturbed. However, because of their venomous spines and ability to produce electrical currents, live specimens should be handled with care.

Where I learned about southern stargazers, and you can too!

Texas Marine Species
txmarspecies.tamug.edu/fishdetails.cfm?scinameID=Astroscopus%20y-graecum

Fish Base
www.fishbase.se/summary/3704

IUCN Red List
www.iucnredlist.org/species/190348/1948667#text-fields

World Register of Marine Species
www.marinespecies.org/aphia.php?p=taxdetails&id=159252

The South Texas Map
www.stxmaps.com/go/stargazer.html

Florida Museum
www.floridamuseum.ufl.edu/discover-fish/species-profiles/astroscopus-y-graecum/

Smithsonian Tropical Research Institute
biogeodb.stri.si.edu/caribbean/en/thefishes/species/3928

National Park Service
www.nps.gov/pais/learn/nature/fish.htm

JSTOR
www.jstor.org/stable/7905?seq=1#page_scan_tab_contents

iNaturalist
www.inaturalist.org/taxa/179509-Astroscopus-y-graecum

What’s That Fish?
www.whatsthatfish.com/fish/southern-stargazer/1711#5

AquaViews
www.leisurepro.com/blog/explore-the-blue/stargazer/

Animal Planet
animalplanet85.blogspot.com/2018/04/stargazer-fish.html