Creature Feature: Shovelnose guitarfish

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You can guess that the shovelnose guitarfish (Rhinobatos productus) gets its name from its long shovel-like snout and guitar shape body. Their sandy coloration allows them to camouflage at the bottom, where they burrow themselves under the substrate. They leave only their eyes above the mud to see unsuspecting prey.

The guitarfish mouth is located on the underside of the head allowing them to feed on benthic organisms like crabs and clams.  Like many chondrichthyans (animals that have cartilage instead of bones) these fish have spiracles on top of their body that pass water through and out their gills on the underside.

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Shovelnose guitarfish are ancient elasmobranchs (sharks, rays and skates which are cartilaginous fishes) that have been around for almost 100 million years. They are sometimes described as an evolutionary blend of rays and sharks having features of both organisms. These amazing, ancient creatures are found from San Francisco Bay to the Gulf of California.

 

This species is affected by human activity, and their population is struggling so much that they are nearly considered “threatened”. One cause is that of shovelnose  fishing industries in Baja and the Gulf of California. Another issue is that these fish get caught in bycatch from other commercial fishers throughout their habitat range. In addition to commercial fishing, habitat destruction and pollution threatens guitarfish. Runoff carries pollutants into the water, causing a cascade of effects on the entire ecosystem. Similarly, dredging the benthic habitat that supports guitarfish and many other organisms destroys the habitat and the food chains connected to it.

We do encounter shovelnose guitarfish in the Bay—you can get a chance to see them on a Marine Science Institute Discovery Ecotour.

References:

http://www.montereybayaquarium.org/animal-guide/fishes/shovelnose-guitarfish

http://aquariumofthebay.org/pages/detail/1579

http://www.fishbase.org/summary/2549

Photographs: Marine Science Institute Database

 

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