How many species of sea urchin are there?
Sea urchin
Sea urchins or urchins (/ˈɜːrtʃɪnz/) are typically spiny, globular animals, echinoderms in the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres (16,000ft; 2,700 fathoms).[1] Their tests (hard shells) are round and spiny, typically from 3 to 10cm (1 to 4in) across. Sea urchins move slowly, crawling with their tube feet, and sometimes pushing themselves with their spines. They feed primarily on algae but also eat slow-moving or sessile animals. Their predators include sea otters, starfish, wolf eels, and triggerfish.
Sea turtle
The IUCN Red List classifies three species of sea turtle as either "Endangered" or "Critically Endangered". An additional three species are classified as "Vulnerable". The flatback is considered as "Data Deficient", meaning that its conservation status is unclear due to lack of data. All species of sea turtle are listed in CITESAppendix I, restricting international trade of sea turtles and sea turtle products. However, the usefulness of global assessments for sea turtles has been questioned, particularly due to the presence of distinct genetic stocks and spatially separated regional management units (RMUs). Each RMU is subject to a unique set of threats that generally cross jurisdictional boundaries, resulting in some sub-populations of the same species' showing recovery while others continue to decline. This has triggered the IUCN to conduct threat assessments at the sub-population level for some species recently. These new assessments have highlighted an unexpected mismatch between where conservation relevant science has been conducted on sea turtles, and where these is the greatest need for conservation. For example, as at August 2017, about 69% of studies using stable isotope analysis to understand the foraging distribution of sea turtles have been conducted in RMUs listed as 'Least Concern' by the IUCN.