The Caribbean reef shark is a viviparous species, meaning its developing embryos are nourished via a placental connection. The litters average four to six pups. Although this shark’s reproduction has not been studied in the northern hemisphere, but to the south, parturition occurs during the Amazon summer of November to December. Pregnant females are often found to have biting scars from males on the sides of their bodies, due to the aggressive behaviors of males during mating. Gestation is believed to take approximately one year. A pregnant female with biting scars and wounds on the sides of her body, taken off the coast of north-northeastern Brazil, carried four near-term embryos. One was a 27.5 in. (700 mm) long male and three were females measuring 27.0 in. (685 mm), 27.4 in. (697 mm), and 27.7 in. (704 mm) in length. Because she was carrying near-term embryos, it is postulated that this area may be a pupping ground. Although such captures have shed light on the topic, relatively little is known about the reproduction of the Caribbean reef shark. Much information has been obtained from a pregnant female carrying four near-term embryos off the coast of northeastern Brazil. This female had scars and wounds on her side. Because the shark carried near-term embryos, it is postulated that this area may be a pupping ground.
One useful definition distinguishes reefs from mounds as follows: Both are considered to be varieties of organosedimentary buildups – sedimentary features, built by the interaction of organisms and their environment, that have synoptic relief and whose biotic composition differs from that found on and beneath the surrounding sea floor. Reefs are held up by a macroscopic skeletal framework. Coral reefs are an excellent example of this kind. Corals and calcareous algae grow on top of one another and form a three-dimensional framework that is modified in various ways by other organisms and inorganic processes. By contrast, mounds lack a macroscopic skeletal framework (see stromatolite). Mounds are built by microorganisms or by organisms that don't grow a skeletal framework. A microbial mound might be built exclusively or primarily by cyanobacteria. Excellent examples of biostromes formed by cyanobacteria occur in the Great Salt Lake in Utah, and in Shark Bay on the coast of Western Australia.
Measuring up to 3 m (9.8 ft) long, the Caribbean reef shark is one of the largest apex predators in the reef ecosystem, feeding on a variety of fishes and cephalopods. They have been documented resting motionless on the sea bottom or inside caves, unusual behavior for an active-swimming shark. If threatened, it may perform a threat display in which it frequently changes direction and dips its pectoral fins. Like other requiem sharks, it is viviparous with females giving birth to 4–6 young every other year. Caribbean reef sharks are of some importance to fisheries as a source of meat, leather, liver oil, and fishmeal, but recently they have become more valuable as an ecotourist attraction. In the Bahamas and elsewhere, bait is used to attract them to groups of divers in controversial "shark feedings". This species is responsible for a small number of attacks on humans. The shark attacks usually happen in spring and summer.
There is a variety of biotic reef types, including oyster reefs and sponge reefs, but the most massive and widely distributed are tropical coral reefs. Although corals are major contributors to the framework and bulk material comprising a coral reef; the organisms most responsible for reef growth against the constant assault from ocean waves are calcareous algae, especially, although not entirely, coralline algae.
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