In what may provide insights into the evolutionary history of Antarctica, scientists claim to have found evidence that sea spiders contain secrets to the Antarctic evolution through age, distribution and diversity. An international team, led by Dr Claudia Arango of Queensland Museum, has based its findings on an analysis of a large collection of these long-legged marine invertebrates acquired during recent Antarctic voyages. Dr Arango said: "Pycnogonids are very ancient; we know of a larva from the Cambrian period 500 million years ago and an adult from the Silurian period about 425 million years ago. "They are also widely distributed and diverse. They occur in tropical, temperate and polar oceans, from shallow water to abyssal depths; they range in size from 1 mm to over 70 cm in leg span; and about 20 per cent of the world's known species — about 1350 — are found in Antarctica." The age, distribution and diversity of sea spiders makes them useful for studying evolutionary history because large-scale events, such as glaciations and the isolation of Antarctica by the Antarctic Circumpolar Current, can be tracked by trends in the distribution of pycnogonid species, say the scientists.
To detect such trends, the team is initially examining the distribution pattern of most common pycnogonid species — Nymphon australe.