Two new species of Sawsharks discovered
- Posted By
10Pointer
- Categories
Environment
- Published
24th Mar, 2020
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- The newly discovered Pliotrema kajae and Pliotrema annae – affectionately known as Kaja’s and Anna’s six-gill sawsharks – were discovered during research investigating small-scale fisheries operating off the coasts of Madagascar and Zanzibar.
- The discovery re-enforces both how important the western Indian Ocean is in terms of shark and ray biodiversity, but also how much we still don’t know.
- As its name suggests, the sawshark is a type of shark best known for its saw-like snout. Found mainly in the temperate waters of all three major oceans (with the centre of distribution in the western Pacific Ocean), the number of sawsharks has declined in the past couple of decades due to commercial fishing.
- Sawsharks can reach up to about 1.5 metres in length and have a long snout edged with sharp teeth which alternate in size (smaller teeth are inserted between larger teeth).
- They also has a distinctive pair of barbels in the middle of the snout – whisker-like sensory organs around the shark’s mouth which help the shark detect its prey.
- Sawfish are larger, they don’t have barbels, and their gills are located on the bottom side of the body (like typical for rays).
- Sawsharks are carnivores, living on a diet of fish, crustaceans and squid, and use their serrated snout to kill their prey. Fast movement of the snout from side to side cuts the prey into fine pieces that can be swallowed easily.
- Both new species differ from the only previously known six-gill species, Pliotrema warreni, in the position of their barbels: in P. kajae and P. annae, these are situated approximately half way from the tip of the saw – the rostral tip – to the mouth, compared to P. warreni, where they are about two thirds of the way down, much closer to the mouth.
- A special feature of P. annaeis the generally shorter rostrum as compared to P. kajae and P. warreni.
