Seamounts
From the deep waters on the continental slope and abyssal plain, large underwater mountain peaks rise towards the surface. Deep water, rugged terrain, steep slopes, strong ocean currents, low light and extreme water pressures make it a difficult place to live – and explore.
Photo: Tony Koslow and CSIRO Marine and Atmospheric Research.
However, scientific knowledge of seamounts, the remnants of long-extinct volcanoes, is slowly growing. It is now known that they support a remarkable collection of marine animals including stony corals, sponges, brachiopods, crustaceans, sea urchins, sea pens, sea spiders, moray cods and orange roughy. The unique deepwater coral and echinoid communities found between the South Tasman Rise and the Tasmanian coast have been given some protection in the recently declared Tasmanian Seamounts Reserve.
Orange Roughy (Hoplostethus atlanticus)* 
Photo: David Paul.
The orange roughy’s habit of spawning in large aggregations in deep water on the seamounts of Australia’s southern temperate waters made it an easy target in the late 1980s for Australia’s fishing fleets in search of new species to harvest. With its firm and relatively odourless flesh that lost little quality with freezing, and the ease with which it was filleted boneless, orange roughy became popular in the high-end US and Australian markets. In the early 1990s catches peaked at 50,000 tonnes per year, but overfishing of this long-lived but slow to reproduce species sees catches set now at less than 3,000 tonnes, and most roughy fishing areas in Australian waters to be closed by fisheries regulators. The orange roughy still aggregates to spawn, but there are no very large aggregations remaining.
The orange roughy belongs to the slimehead family (Trachichthyidae). It can grow up to 75cm however, the average size is 30-40cm. It feeds on zooplankton and have a long life span. Most reach over 100 years but one specimen was aged at more than 200!
Prickly Deep Sea Anglerfish Echinophryne crassispina 
Photo: David Paul/Mark Norman
Extreme water pressures, lack of sunlight and turbulent water make some deep sea fish come up with strange shapes and behaviours to survive. The Prickly Deep Sea Anglerfish is one of them and has spines shaped like a lure to look like their prey and a rod (dorsal spine) to attract and catch its food. A relatively large mouth helps rapidly strike within one hundreth of a second. The anglerfish is rarely seen because of its obscure appearance.
Mating within this species is quite unique. Due to the lack of light underwater, male anglerfish have to detect the pheromones the females release. They then attach themselves in a parasitic fashion (by biting) and release sperm when the female’s eggs are discharged.