STINGRAYS

Stingrays are a group of rays, which are cartilaginous fishes related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes, and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatidae (deep water stingray), Urolophidae (stingarees), Urotrygonidae (round rays), Dasyatidae (whiptail stingrays), Potamotrygonidae (river stingrays), Gymnuridae (butterfly rays), and Myliobatidae (eagle rays).

Most stingrays have one or more barbed stings (modified from dermal denticles) on the tail, which are used exclusively in self-defense. The stinger may reach a length of approximately 35 cm (14 in), and its underside has two grooves with venom glands. The stinger is covered with a thin layer of skin, the integumentary sheath, in which the venom is concentrated. A few members of the suborder, such as the manta rays and the porcupine ray, do not have stingers.

Stingrays are common in coastal tropical and subtropical marine waters throughout the world, and also includes species found in warmer temperate oceans, such as Dasyatis thetidis, and those found in the deep ocean, such as Plesiobatis daviesi. The river stingrays, and a number of whiptail stingrays (such as the Niger stingray), are restricted to fresh water. Most myliobatoids are demersal, but some, such as the pelagic stingray and the eagle rays, are pelagic.

While most stingrays are relatively widespread and not currently threatened, for several species (for example Taeniura meyeni, D. colarensis, D. garouaensis, and D. laosensis), the conservation status is more problematic, leading to them being listed as vulnerable or endangered by IUCN. The status of several other species are poorly known, leading to them being listed as Data Deficient.

SEA HORSE

Seahorse is the title given to 54 species of marine fish in the genus Hippocampus. "Hippocampus" comes from the Ancient Greek hippos meaning "horse" and kampos meaning "sea monster".

Location

Seahorses are mainly found in shallow tropical and temperate waters throughout the world, and prefer to live in sheltered areas such as seagrass beds, estuaries, coral reefs, or mangroves. In Pacific waters from North America to South America there are approximately four species. In the Atlantic, the H. erectus ranges from Nova Scotia to Uruguay. H. zosterae, known as the dwarf seahorse, is found in the Bahamas.

Colonies have been found in European waters such as the Thames Estuary.

Three species live in the Mediterranean Sea: H. guttulatus (the long-snouted seahorse), H. hippocampus (the short-snouted seahorse) and H. fuscus (the sea pony). These species form territories; males stay within 1 square meter (11 sq ft) of their habitat while females range about one hundred times that.

DIVING WET SUIT

A wetsuit is a garment, usually made of foamed neoprene, which is worn by surfers, divers, windsurfers, canoeists, and others engaged in water sports, providing thermal insulation, abrasion resistance and buoyancy. The insulation properties depend on bubbles of gas enclosed within the material, which reduce its ability to conduct heat. The bubbles also give the wetsuit a low density, providing buoyancy in water.

The layer of warm water normally trapped between the suit and the skin provides very little thermal insulation, contrary to popular beliefs regarding wetsuits.

Hugh Bradner, a University of California, Berkeley physicist invented the modern wetsuit in 1951. Wetsuits became available in the mid-1950s and evolved as the relatively fragile foamed neoprene was first backed, and later sandwiched, with thin sheets of tougher material such as nylon or later Lycra/Spandex. Improvements in the way joints in the wetsuit were made by gluing, taping and blindstitching, helped the suit to remain waterproof and reduce flushing, the replacement of water trapped between suit and body by cold water from the outside. Further improvements in the seals at the neck, wrists and ankles produced a suit known as a "semi-dry".

Different types of wetsuit are made for different uses and for different temperatures. Suits range from a thin (2 mm or less) "shortie", covering just the torso, to a full 8 mm semi-dry, usually complemented by neoprene boots, gloves and hood.