Fish and Coral Information
The manta ray, or cheap manta (Manta birostris), is the largest of the rays, with the largest known specimen having been about 7.6 m (about 25 ft) across.
Evolution and taxonomy
Manta rays are believed by some to have evolved from bottom-feeding ancestry, but have adapted to become filter feeders in the open ocean. This allowed them to grow to a larger size than any other species of ray. Because of their pelagic lifestyle as plankton feeders, some of the ancestral characteristics have degenerated. For example, all that is left of their oral teeth is a small band of vestigial teeth on the lower jaw, almost hidden by the skin. Their dermal denticles are also greatly reduced in number and size, but are still present, and they have a much thicker body mucus coating than other rays. Their spiracles have become small and non-functional, as all water is taken in through their mouth instead. Mantas are filter feeders: they feed on plankton, fish larvae and the like, passively filtered from the water passing through their gills as they swim. The small prey organisms are caught on flat horizontal plates of russet-coloured spongy tissue, that span the spaces between the manta's gill bars. Mantas frequent reef-side cleaning stations where small fish such as wrasses and angelfish swim inside the manta's gills and all over its skin to feed, in the process cleaning it of parasites and removing bits of dead skin. The predators of the Manta ray include mainly large sharks, however in some circumstances orcas have also been observed preying on them. Mantas are extremely curious around humans, and are fond of swimming with scuba divers. Although they may approach humans, if touched, their mucus membrane is removed, causing lesions and infections on their skin. They will often surface to investigate boats (without engines running). They have the largest brain-to-body ratio of the sharks and rays. Mantas are known to breach the water into the air.