The shy hamlets (''Hypoplectrus guttavarius'') are small Western Atlantic
serranids of the genus
Hypoplectrus
''Hypoplectrus'' is a genus of fishes commonly known as hamlets, found mainly in coral reefs in the Caribbean Sea and the Gulf of Mexico, particularly around Florida and the Bahamas. They are a popular choice for hobbyist saltwater aquariums, and ...
, which belong to the subclass
perciformes
Perciformes (), also called the Percomorpha or Acanthopteri, is an order or superorder of ray-finned fish. If considered a single order, they are the most numerous order of vertebrates, containing about 41% of all bony fish. Perciformes means ...
in the class
Actinopterygii
Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species.
The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...
(ray-finned fishes). To this date, seventeen species of the genus have been recognized, a third of which have been discovered in the past few years.
They are synchronous hermaphrodites; ecologically and morphologically, all are remarkably similar in major features except for their color pattern which is how they are differentiated into different species.
The name is derived from its personality because they are solitary species that travel in pairs. They are mostly found in the Western Atlantic Ocean on Caribbean inshore areas in low depths (3-30 m) and in temperatures of about 22-27 ºC (72-80 ºF).
Hamlets are small and bright colored, specifically, shy hamlets have a yellow head and fins followed by a brown-black body. In addition, there are bright blue stripes around the eye and on the snout. They are carnivores and mostly feed on regular aquarium foods including shrimp, clam, squid, etc.
Shy hamlets were first formally described as Plectropoma guttavarium in 1852 by the Cuban zoologist
Felipe Poey
Felipe Poey (May 26, 1799 – January 28, 1891) was a Cuban zoologist.
Biography
Poey was born in Havana, the son of French and Spanish parents. He spent several years (1804 to 1807) of his life in Pau then studied law in Madrid. He became a ...
(1799-1891) with Havana given as the type of locality
Description
Hamlets are small and bright colored. Shy hamlets have a yellow head with a brown-black body. However, the extent of the two-color potions can vary, and they are divided by a diagonal line extending from the nape posteriorly and ventrally to the anal fin. The face and all the fins are yellow. On the head it has a bright blue streak around the eye and on the snout. In addition, they can grow up to a maximum size of 13 cm (5 in) in length.
In the past, researchers described hamlets as members of single species called H. unicolor. However, more recent work has suggested that several of those species are likely within the same group. Until today, opinions of scientists remain divided concerning these two hypotheses and have been described as the "Hamlet Problem" by the American ecologist
Ron Thresher. The only character, thus far, found to be different and specific to each species is coloration and geographic distribution. In fact, studies have found that mating hamlets produce a unique sound while gametes are dispersed which might help to synchronize spawning. They also produce a low amplitude pre-mating sound, which have been hypothesized to be characteristic to different hamlet species, although it has not been statistically validated. More recent work has suggested that there is some small degree of genetic isolation between geographically separated species, although it is not an absolute pattern.
Distribution and Habitat
The shy hamlet inhabits the tropical Caribbean seas. The fish is primarily
pelagic
The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...
and can be found on inshore areas in low depths (3-30 m) in temperatures of about 22-27 ºC (72-80 ºF). They are coral reef fishes that vary in their distribution but tend to be highly sympatric, with up to nine species found on a single reef.
In a study of the distribution of hamlets in the Greater Caribbean region using cluster and nMDS analyses, where hamlets were divided into three major groups: widespread, less widespread, where the shy hamlets belong to and geographically confined or segregated.
Reproduction
Shy hamlets are
simultaneous hermaphrodites, meaning they possess both female and male reproductive systems. Observational studies have shown that hamlets mate only in pairs, with
external fertilization
External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body.
It is contrasted with internal fertilization, in which sperm are introduced via insemination and then ...
and planktonic zygotes. They display stronger mating preference for species of the same color pattern. However, there has been occasional mixed matings and hybrids, where the offspring have mixed coloration.
Mating usually occurs right before sunset and continues for a small period after sunset. They purposely choose a spawning location above a tall reef structure allowing them to mate relatively high in the water column. This serves the purpose of placing the free-floating eggs in a location with higher chance to be carried away by the current to avoid being preyed upon by predators roaming the sea floor.
During mating, once the proper height is attained, shy hamlets take turns fertilizing each other's eggs by wrapping themselves around each other and vigorously shaking, releasing eggs and sperm into the water column.
Shy hamlets continue to reproduce even upon disruptions, by trying to mate more frequently in the same period of spawning or by continuing to go even later past sunset to ensure fertilization of eggs. Sometimes when predators are disturbing, they have also shown the ability to spawn lower, closer to the seafloor to hide themselves.
Diet
Shy hamlets are reef-associated carnivorous predatory fishes. While little is known about what the Shy Hamlet specifically eats, other species of Hamlets have been known to feed on smaller fish, crustaceans, and shrimp. For crustaceans, Hamlets have been known to eat
Mysid shrimp
Mysida is an order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch or "marsupium" in females. The fact that the larvae are reared in ...
,
crabs
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...
, and
Mantis shrimps. While for fishes, Hamlets have been observed to eat
Chrysiptera cyanea
''Chrysiptera cyanea'' is a species of damselfish found in the wide Indo-West Pacific but not known in the Red Sea.Froese, R. and D. Pauly, Eds''Chrysiptera cyanea''.FishBase. 2011. A few individuals were observed in the Mediterranean Sea in 2013 ...
.
References
guttavarius
Fish of the Atlantic Ocean
Fish of the Dominican Republic
Fish described in 1852
Taxa named by Felipe Poey
{{Serranidae-stub