Long-spined spine Squirrel fish
The long-spine squirrelfish is in the Holocentridae family, which is made up of ray-finned fish with two subfamilies: the Myripristinae family, which includes the soldierfish, and the Holocentridae family, which includes the squirrelfish. Because they eat meat at night, squirrelfish are easiest to see at night. These fish are about the size of a golf ball and are bright red. They have big, rough scales, sharp spines, and small teeth. People know them for their big eyes, the spines that stick out of their operculum, and their ability to make noise. The poison can come out of the sharp spines. The Holocentrus rufus fish lives near the bottom of warm, shallow reefs.
Land Use
This species, H. rufus, is also called the longspine squirrelfish. It lives in the warm tropical seas of the western Atlantic Ocean, from the southern United States to northern South America. This species lives in coral and rocky reefs up to 100 meters deep, but most of the time it stays in water less than 50 meters deep. The H. rufus fish only comes out at night and hides during the day in a hole or cave made by the reef structure. For this species, the best kinds of cover are ones that are higher up and built into a steep surface, like an overhang. Longspine squirrelfish are very territorial, so they don’t let other animals of the same species or enemies that are a bit bigger into their homes. Some people guard more than one shelter that could be used as a backup. People often see them in small groups of eight to ten. At night, H. rufus goes away from the reef and into sea grass beds and sandy areas to hunt its prey, which includes crabs, shrimp, gastropods, and brittle stars. Due to the fact that they have to swallow whole food, squirrelfish can only eat small prey.
Reproduction and the circle of life
Like many other marine animals, squirrelfish breed by having eggs laid by other animals. They do not care for their young. They usually have two times a year when they can breed. H. rufus has a complicated life cycle with steps that happen in the water and on land (Bowen et al., 2006). Holocentridae species have a unique stage of life after they hatch called rhynchichthys (Tyler et al., 2003). Five spines can be found on the rostral, in front, at the operculum, and at the supraoccipital bone of the migratory rhynchichthys (Coad and McAllister, 2010). The body length is thought to be about 25 mm at this point (Tyler et al., 2003). After going through the rhynchichthys stage, the organism moves on to the next pelagic stage, which is often called meeki. By this time, the body’s spines are less noticeable because it have become more streamlined (Tyler et al., 2003). The color stays silvery, and most of them are about 55 mm long (Tyler et al., 2003). Many other species don’t have this stretch of the pelagic level, which lets H. rufus quickly change into its benthic juvenile life stage when the conditions are right (Bowen et al., 2006). When they are young, they turn a reddish-orange color. Some can go from silver to red-orange in just one night (Tyler et al., 2003). The squirrelfish grows slowly and lives a pretty long time (unknown). In general, an adult is about 20 cm long (Froese and Pauly, 2011).
More recent research
There are fish, like squirrelfish, that can make grunting sounds. Muscles move the ribs around the swim bladder, which makes these sounds (Winn and Marshall, 1963). The nerve system controls these sounds. These sounds have a low frequency and happen all day. At night, they have a higher frequency (Luczkovich and Keusenkothen, 2007). The meanings of these sounds are being studied right now. Studies have shown that H. rufus uses sounds to fight and send out warning calls with other members of the same species (Luczkovich and Keusenkothen, 2007). Furthermore, it has been shown that H. rufus can tell if an attacker is dangerous by the sound it makes.
Research into the effects of big storms and the damage they do to reef habitats is growing. Scientists are looking at squirrelfish populations and where they live, as well as their enemies and prey, in the years after a big event. By comparing the data sets, we can see how storms change the locations of species and the damage they cause to coral reef habitats (Kaufman, 1983).
Result on the economy
People don’t really care about squirrelfish as food. Even though they can be eaten and have been said to taste good, most people don’t because they are small and can stay alive in traps for a long time (Chapman et al., 1980). Instead, they are mostly worth money because they are sold to tanks all over the world. People want to buy H. rufus because of its bright color and big eyes. They are good for tank owners because they aren’t too big compared to other squirrelfish.
