快猫短视频

Species:

Habitat: seafloors 3 to 73 metres down along the coasts of California and Baja California

Sarcastic fringeheads have a stronger temper than your average fish, but it isn鈥檛 a sharp tongue that you have to look out for: it鈥檚 their gaping, fluorescent mouth.

When threatened by other males, these fish can open their mouths about as large as their entire head, displaying an outer and inner row of teeth. It鈥檚 all an effort to show other fringeheads that 鈥淚鈥檓 bigger than you and you shouldn鈥檛 come into my area,鈥� says at the University of California Los Angeles.

While working at the Scripps Institution of Oceanography in California, Hongjamrassilp studied how the fringeheads can open their mouths so wide.

Seriously weird name

Sarcastic fringeheads are about 20 to 30 centimetres long, with very large heads in proportion to their bodies. They may have been named for the sardonic expression they appear to have if you encounter them with their mouths closed.

Male sarcastic fringeheads generally like to live in old snail shells or clam burrows, but they aren鈥檛 above more modern living arrangements like bottles or cans. They ambush or hunt down passing octopuses, or crustaceans that like to live in the same nooks and crannies on the seafloor, Hongjamrassilp says. That is, when they aren鈥檛 opening their mouths at each other.

Hongjamrassilp and his colleagues found that sarcastic fringeheads can extend their mouths so much because their upper jaw bone is extremely long. It flares out to the sides when the fish opens its mouth. The fringeheads also have unusually extensive cheek membranes, which hang off these bones like sails on a boat.

The team has also found that the inside frame of their mouth 鈥� the bit that looks like their lips, although they don鈥檛 technically have lips 鈥� is fluorescent yellow. The rest of the inside of their cheeks reflects ultraviolet light. These traits make the fringeheads鈥� mouths more conspicuous in the dark and sometimes murky water they call home.

Bigmouth strikes again

As well as trying to scare each other away with their gaping mouths, the fringeheads sometimes use them to wrestle each other. This can look like a vigorous piscine make-out session. A fingehead can sometimes fit half its opponent鈥檚 head into its mouth.

They will even resort to biting their opponents, but Hongjamrassilp says this doesn鈥檛 seem to do much damage. 鈥淭he loser swims away,鈥� he says.

Curiously, the one thing the males don鈥檛 use their big mouths for is courting females. Instead, they pop their big heads out of their homes, then shake their heads back and forth as if to say 鈥渘o鈥�.

It鈥檚 unclear how sarcastic fringehead females choose their mates, but Hongjamrassilp says suggests the male who shakes his head most vigorously will win females鈥� hearts.