Blind Electric Ray

1/27/2016

We’ve talked about blind things before at Sarasota Fins, so is it any surprise that we’re bringing up another sight-less creature?

Well, the blind electric ray isn’t technically blind (as neither was the blind shark)… it just has tiny eyes that aren’t really visible, instead being beneath the surface of their skin.

“Excuse me, what?”

Yeah. Freaky, huh? It leads to them having pretty bad eyesight either way, but I wouldn’t completely label them as “blind.”

Now, the specific blind electric ray we’re talking about today is Typhlonarke aysoni. There’s another two: the Brazilian blind electric ray (Benthobatis kreffti; endemic to Brazil) and the Taiwanese Blind Electric Ray (Benthobatis yangi; endemic to Taiwan).
Typhlonarke aysoni is endemic to… you can’t guess it, can you? It’s not in the common name, like it seems to always be when it comes to these guys. Yet, I get to share waters with these guys- yup, they’re endemic to New Zealand! They’re usually found around Cook Strait (and on the continental shelves and slopes that are southward from there), anywhere from 100-900 meters (328-2,952 ft) deep.

Also known as the “blind legged torpedo” (I can’t help but giggle at that name) or “numbfish,” this deep-watered ray has an interesting genus name, “Typhlonarke,” that explains its common names. “Typhlops” is Greek, translating to “blind” and “narke” is also Greek, roughly translating to “numbness” or “paralysis.” And while it may be electric (zap!) the organs capable of producing their electric discharge varies between 8 volts and 220 volts. No worries, though- at that depth, they pose no threat to you. They do pose a threat to their prey (like polychaete worms, for example), though.

It is a very small (15-30 cm), poorly-known electric ray. Like other Torpediniformes, they sport a typical round shape, a small and soft tail, and one dorsal fin. They are dark brown in color, and don’t seem to be the most graceful swimmers, so they probably use their pelvic fins to “walk” along the floor. It’s kind of cute to picture.

Electric rays are viviparous with yolk-sac and reproduce slowly.

The International Union for Conservation of Nature (IUCN) doesn’t have enough data on these rays to be able to assess its conservation status, though it is thought to be potentially vulnerable due to its distribution coinciding with major trawl fishery grounds. It is currently assessed as Data Deficient (DD). Its exact distribution isn’t know, though, since it’s often confused with the oval electric ray, Typhlonarke tarakea. The marine sanctuaries around New Zealand provide a little bit of relief! (Shout out to the Prime Minister John Key for announcing the creation of a massive marine sanctuary at the Kermadecs, about 1,000 km NE of New Zealand. The “Kermadec Ocean Sanctuary” will cover about 620,000 square kilometres, which is 50 times bigger than New Zealand’s current biggest national park! Woo hoo!)

Did you know about this "blind" critter before?

glossary

Dorsal fin: Fin located on the back.
Endemic: Native to a specific region or environment and not occurring naturally anywhere else.
Genus: A group of organisms ranking above a species and below a family.
IUCN: International Union for Conservation of Nature.
Marine sanctuaries: A general type of marine protected area (MPA). An MPA is a section of the ocean where a government has placed limits on human activity.
Pelvis fins: Fins located behind the gills on either side.
Polychaete worms: Multi-segmented worms living in all environments in the world's oceans.
Torpediniformes: Order of the electric rays.
Trawl fisheries: Fisheries that pull a fishing net through the water behind one or more boats.
Viviparous with yolk-sac: Also known as aplacental viviparous and previously known as ovoviviparous/ovoviviparity; it is the production of eggs that are fertilised and hatch inside the female shark but the embryos lack a placental connection to the oviduct or uterus and so do not feed off the mother.