DEEP SEA Elasmobranchs
The deep-sea is defined as the part of the ocean below 200 meters ( 656 feet) depth. This is where light begins to dwindle. Deep-water ecosystems are unlike any other habitat on the planet.
Despite being the most extensive habitat on our planet, we know very little about this mysterious world. Surprisingly, even with the challenges of darkness, cold temperatures and increased pressure, life is able to thrive at these depths and biodiversity is higher than once believed.
Deep sea species have special adaptations to deal with the increased pressure and lack of light.
Bioluminescence ( lantern sharks)
6 and 7 gill slits ( for more effiecient oxygen absorption in a lower oxygen environment)
Slow growth and slow metabolism ( Greenland shark)
Ability to maintain neutral buoyancy ( small amount of positive buoyancy found in 2 species)
Nakamura I, Meyer CG, Sato K (2015) Unexpected Positive Buoyancy in Deep Sea Sharks, Hexanchus griseus, and a Echinorhinus cookei. PLoS ONE 10(6): e0127667. https://doi.org/10.1371/journal.pone.0127667
Paulus E (2021) Shedding Light on Deep-Sea Biodiversity- A Highly Vulnerable Habitat in the Face of Anthropogenic Change. Front. Mar. Sci. 8:667048. doi: 10.3389/fmars.2021.667048.
SIMPFENDORFER, C., & KYNE, P. (2009). Limited potential to recover from overfishing raises concerns for deep-sea sharks, rays and chimaeras. Environmental Conservation, 36(2), 97-103. doi:10.1017/S0376892909990191.
NOAA Ocean Exploration https://oceanexplorer.noaa.gov/facts/deep-ocean.html