Bonaire: one of the premiere diving locations in the world. There are many reasons, including the supportive infrastructure, the diving freedom, wealth of diving sites and the relative clarity of the water. But another feature that I personally appreciate is the existence of something interesting to observe at virtually all dive-able depths. One consequence of this is that there is no need for a boring safety stop spent hanging in the water column. Instead, one can use up the corresponding time and depth on the sandy shelf to see creatures that are unique to that environment. There is much to see, including the three western Atlantic members of the Razorfish genus (Xyrichtys), of which there are 25 members world-wide. Members of the Wrasse family, razorfish get their name from their razor-thin bodies that are very laterally compressed with a sharp bony ridge at the front of their heads. This adaptation allows them to dive headfirst very quickly into the sand at any sign of danger, an essential strategy for survival on the sand plains bereft of other cover.
Like the other wrasses, razorfish exhibit sequential hermaphroditism, beginning life as female but possessing the ability to transform into a terminal male under the right conditions. Indeed, razorfish have three distinct color phases representing their social status: the juvenile phase consisting of immature youngsters, the initial phase consisting of adult females, and the terminal phase consisting of males. Each razorfish species occupies semi-permanent territories in association with other members of its kind. They begin their life as pelagic larvae that settle to a reef environment after an extended period of up to three months. Each of the three Bonairean razorfish are territorial, living in relatively small and relatively stable areas, in colonies consisting of multiple separate harems consisting of a few males and a number of females.
Question: What is so special about razorfish?
Answer: Their behaviors and their appearance.
Green Razorfish are perhaps the most common and the easiest to approach. They characteristically ‘hide’ by curling their bodies and remaining still close to a piece of debris, diving into the sand only as a last resort.
Rosy Razorfish are also common. Although they eat crustaceans, they primarily rely on diets of zooplankton plucked from the currents, which perhaps explains their very distinctive habit of bobbing up and down near the bottom.
They live grouped together in tightly packed colonies consisting of multiple harems. Each harem consists of at least one dominant male and from three to 30 initial phase females each of which occupies a sandy patch only a few feet in diameter. Occasionally the entire colony moves to a new area.
Spawning occurs late in the day; mostly between 2:30 and 4:00pm. Females are courted by the male before spawning takes place. The male tips into a head-down posture in front of the female while rigidly extending his fins and intensifying his colors. This is followed by the male twitching his body once or twice, and then swooping around her into a head- up posture. The display is repeated often and, if no consenting activity of the female is forthcoming, the male leaves to court other females or patrol the edges of his territory. If the female responds by initiating a slow rise in the water column, the male joins her with his head touching her operculum and they rise about a meter before returning to the substrate in a dash. The actual release of gametes occurs at the apex of the rise. After 4:00pm the razorfish are progressively less active and stay closer to the substrate until about 5:30pm by which time all will have burrowed into their sand refuges for the night. Apparently females of this species spawn daily.
Least common, at least in my experience, are the Pearly Razorfish, which feed on small invertebrates such as crustaceans, mollusks and echinoderms, so they are usually observed moving about dipping their snouts into the sand. Their harems appear to be larger in diameter but less dense than the other razorfish, and they are much less approachable than their cousins. Whereas Rosy Razorfish males occasionally succumb to the temptation of taking a bite or two of the newly fertilized gametes after spawning, this behavior has never been recorded for Pearly Razorfish.
The next time you dive where there is a sandy shelf, don’t hang in the water column for a boring safety stop; instead look for the fascinating Razorfish.
WHAT TO LOOK FOR:
Green Razorfish (Xyrichtys splendens): Length 2.5 – 4in. Depths 5 – 35ft. Colors vary greatly, but most commonly with a green cast. Eyes have a bright red iris and a green pupil. Margin of tail rounded. Terminal phase: Males have a dark spot (occasionally two) at the midbody and may have bars and markings ranging from reddish brown to yellow, green and white. Females have no distinctive marks, but may have bars. Juvenile phase: First two dorsal spines are long, with pigmented tissue in between. The rest of the dorsal fin is clear, with two or three pigmented bars, the rear two of which correspond to similar bars on the anal fin.
Rosy Razorfish (Xyrichtys marinicensis): Length 3 – 4.5in. Depths 5 – 35ft. Margin of tail is straight. Terminal phase: Males have a mixture of pastel green, blue and yellow. The head is usually pale yellow with faint bars. There is a darkened area at the base of the pectoral fin. Female is grayish to rosy pearl, with a pearl white head, a white belly patch with reddish line markings behind the pectoral fin and a darkish bar on the gill cover.
Pearly Razorfish (Xyrichtys novacula): Length 5 – 10in. Depths 10 – 100ft. Margin of tail is rounded. Extremely steep snout, which give the head a squared-off appearance. Small eyes are set high up. Vertical narrow blue lines on head. Males have a wide, diagonal, dusky or reddish band on their sides and females have a white area on the upper belly.
An avid amateur photographer, Charles Shipley was a Professor of Computer Science until his retirement in 2005, when he and his wife Barbara moved aboard their Kadey-Krogen 48 North Sea Tusen Takk II. They have been cruising the Caribbean since January 2007.