The deep-sea is our planet’s final great mystery. We have a poor understanding of the life that inhabits many of the ocean’s remote regions, and one of these regions is a series of seamounts along the Walvis Ridge off of Namibia. I am part of a team of researchers working with SEAFO, the EAF-Nansen project, and the FAO Deep-sea program to explore these seamounts and see if they are capable of sustaining the pressures of commercial fisheries. We will be assessing each area and looking for vulnerable deep-sea life, such as coral, sponges, and sharks.
I am fortunate enough to assist the team in studying the chondrichthyans (sharks, skates, and rays) of the region. I am really excited because this is a new area for me and I know there are some strange deep-sea sharks out here. I am particularly hopeful to see some large ghost sharks called blue pointers (Hydrolagus trolli, named after the artist Ray Troll). They are a large animal (over a meter long) and have been reported from the area. They have big eyes, a tall venomous spine, and get their name from their blue color and pointy noses.
During our sampling at Schmidt Ott and Wüst seamounts we saw some lantern sharks (family Etmoteridae). As their name implies, these sharks are able to generate light along their bellies, flanks, and spines with a process called bioluminescence. They use this light to blend in to the ambient low level lighting (a form a camouflage called counter-illumination). They also use this light to show off their defensive spines to predators, and to communicate with other lantern sharks. A recent study suggests that lantern sharks evolved to have eyes so sensitive to the brief flashes specific to their own species that they can communicate each other’s presences without alerting other animals.
There is still much to learn about sharks and deep-sea species in general. Sharks serve of top predators in nearly all the ecosystems that they inhabit, and because they are so slow to reproduce, understanding their life histories and distributions is key to protecting these deep-sea environments and maintaining a sustainable fishery.
We saw a lot of exciting marine organisms and underwater landscapes at Wüst seamount, and I have really high hopes for Vema seamount and Valdivia Seamount.
Thanks for tuning in!
Guest blogger Paul Clerkin is a graduate student at the Pacific Shark Research Center of Moss Landing Marine Laboratories in southern California. You can follow more of Paul’s research at his blog or on Twitter at @SharkUniversity.
02/02/2015