Bowmouth guitarfish

2/17/2016

Guitarfish are an interesting animal. One of the more recognizable species is the bowmouth guitarfish (Rhina ancylostoma).

The bowmouth guitarfish, also called the "shark ray" or "mud skate," is a species of ray and member of the Rhinidae family. Due to this particular animal looking like a ray and shark got together for a romantic evening together somewhere in their evolutionary paths and created the bowmouth, it is considered by some scientists to be ‘the missing link’ between these two different species.

The reason they’re called "guitarfish" is because they resemble the musical instrument… if it was underwater. I mean, if you want to spend the money to throw a guitar into the ocean, you let us know and we'll be there to let you know if this common name is accurate.

The first part of their name comes from their mouth looking like a longbow, that ancient looking thing we saw Merida wielding (not into Disney Princesses? How about Hawkeye? Legolas? Katniss?).

Bowmouth guitarfish have a few favorites: crustaceans and molluscs. These… interesting… teeth are flat and heavily ridged, allowing for easy crushing of prey. Since their eyes are on top of their head, they utilize their sense of smell to sniff out potential meal, restraining it with its head and giving the animal no escape… but into their mouth.

Speaking of noteworthy characteristics, these animals go through color changes as they age. Juvenile bowmouths are brown with pale spots and black bars behind the eyes. Adults, meanwhile, are black/charcoal in color, with small pale spots, with the black bars fading as time goes on. Some adults decide that dark blue is the new black and opt for that color scheme instead. The ventral side stays a creamy color throughout the animal’s life.

Although they look rather soft, they do have rough denticles that cover their body. The front part of this animal looks like a ray, with a flat, broad arc-shaped head. However, unlike a ray, they have pectoral fins and a caudal fin attached at the end of their tail with two different sized lobes. They sport sharp thorns next to their eyes, the middle part of their back and above their pectoral fins. Some speculate bowmouths headbutt predators/competition with these spikes, but no one has proven- or disproven- this (not that I would want to get headbutted by a spiny fish). These guitarfish can get quite big - almost 3 m/10 ft long- making it hard to play them (ha, guitar puns).

As most rays, these animals prefer shallow, coastal habitats such as coral reefs and mangroves. However, they have been recorded in deeper waters up to 90m (295 ft). They frequent the waters of the Indo-West Pacific being spotted in the Red Sea, East Africa, Japan and Australia (NSW area).

Fertilization in the bowmouth guitarfish is internal, usually giving live birth to four or five pups. Since they are slow to reproduce, they don’t recover quickly from the threats that constantly face them, and are therefore considered Vulnerable (V) by IUCN. They are targeted in some areas, but also commonly caught as bycatch. They are found in some fish markets, as well! Not just for overall consumption, but this is a species that is hunted for its fins due to finning. Although illegal, enforcement is difficult and there is a thriving black market for these items. Pollution due to shoreline development, silting and chemicals are destroying their habitats (primarily coral reefs) as well. This species is also vulnerable to dynamite fishing.

Although there are no major conservation efforts put into place for these critters just yet, the TED devices used to get turtles out of harm’s way have helped a few bowmouth guitarfish escape nets. That’s something to be upbeat about (more guitar puns, yay).

have you seen these animals in an aquarium?

glossary

Crustaceans: Group of animals with a hard exoskeleton, jointed legs and segmented body.
Dermal denticles: Scales found in cartilaginous fishes: sharks, skates, rays, chimaeras.
Dorsal fin: Fin located on the back.
Dorsal side: Top side of an animal.
Dynamite fishing: The practice of using explosives to stun or kill schools of fish for easy collection.
IUCN: International Union for Conservation of Nature.
Molluscs: The largest marine phylum; invertebrate animals, many of which have shells.
Pups: Baby sharks.
Shark finning: the practice of catching sharks slicing their fins off and dumping the animal overboard, many of them still alive.
Ventral side: Underbelly.
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.