Hello #SawfishSaturday! Introducing our first star, the knifetooth sawfish (Anoxypristis cuspidate).
As with many of the animals highlighted at The Fins United Initiative, they go by an array of common names which include the pointed sawfish and narrow sawfish. In the Pristidae family, they are a part of the Batoidea which includes the stingrays and skates. #Finfact: It is the only member of the genus Anoxypristis. You can read more about sawfishes on our “general overview” blog post about them; essentially, they are known for their long, narrow, flattened rostrum that resembles a chainsaw due to their side-ways facing triangular teeth.
The knifetooth sawfish rostrum has 18-22 pairs of teeth in Australian waters; elsewhere, they can have as many as 25 matching pairs. They can get up to 4.7 m (15 ft) long, but tend to be around 2.8 m (9.2 ft); as they grow their skin goes from feeling rather smooth to rough as they become covered in dermal denticles (but sparsely). Knifetooth sawfish are a grey-brown colour on top with a paler grey on both the fins and their underbelly. The teeth on the rostrum are white.
#Finfact: The genus Anoxypristis tends to have a narrower saw than Pristis. So what do they use that rostrum for? They use it to capture prey! Sawfish thrash their rostrum from side-to-side over soft sediment; the action helps stir up the top layer of mud or sand and often unveils a tasty treat for the sawfish. Sawfish can also use their rostrum to incapacitate or stun an individual if they’re amongst a school of fish; their diet includes small fish, squid, and invertebrates. Like many Chondrichthyans, they are both predator and prey. Hammerhead sharks (read our general overview blog post on hammerhead sharks here), the bull shark (Carcharhinus leucas) and bronze whaler sharks (Carcharhinus brachyurus) are some predators this sawfish has… and it also falls prey to saltwater crocodiles (Crocodylus porosus)!
Where would they encounter saltwater crocodiles? Knifetooth sawfish are found all over the Indo-Pacific Ocean from the Red Sea and southern Japan to Papua New Guinea and northern Australia. It’s a bentho-pelagic animal, found up to 40 m (130 ft) deep within its range. They can tolerate low-salinity levels, and are often observed in bays and estuaries (prime saltwater crocodile territory).
Fertilisation for these animals is internal and pups come out with rostral teeth that are not fully developed and are covered by a thick membrane so they don’t hurt momma during their grand entrance into the world. The IUCN has assessed these animals Endangered (EN).
want to see these sharks? so do we!
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TFUI Founder Melissa C. Marquez is author of all animal bios and "Behind the Fins" segments.
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