Alex Mustard,Alex Mustard / A signal blenny (Emblemaria hypacanthus) displays its showy dorsal fin as it extends out of its tube home. La Paz, Mexico. Sea Of Cortez, East Pacific Ocean.

Tony Wu / Striped poison-fang blenny mimic (Petroscirtes breviceps) male inside bivalve shell, guarding eggs laid by different females adhered to inside of shell. Shizuoka Prefecture, Honshu, Japan. June.

Shane Gross / Arrow blenny (Lucayablennius zingaro) peeking out from Fire coral (Millepora dichotoma). Gardens of the Queen National Park, Cuba.

Alex Mustard / Galapagos barnacle blenny (Acanthemblemaria castroi) looking out from its home in an old barnacle shell. Cape Marshall, Isabela Island, Galapagos National Park, Galapagos Islands. East Pacific Ocean....

Linda Pitkin / Spinyhead blenny (Acanthemblemaria spinosa), in a hole in coral Bonaire, Leeward Antilles, Caribbean.

Linda Pitkin / Spinyhead blenny (Acanthemblemaria spinosa), in a hole in coral Bonaire, Leeward Antilles, Caribbean.

Alex Mustard / Spinyhead blenny (Acanthemblemaria spinosa) yawning as its emerges from its hole in a red sponge on a coral reef. This fish was previously identified as the secretary blenny in many sources. Jardines...

Claudio Contreras / Browncheek blenny (Acanthemblemaria crockeri), Angel de la Guarda Island Protected Area, Gulf of California (Sea of Cortez), Mexico, July

Alex Mustard / Spinyhead blenny (Acanthemblemaria spinosa) yawning, on a red sponge. Jardines de la Reina, Gardens of the Queen National Park, Cuba. Caribbean Sea.

Alex Mustard / Close up portrait of small, golden variety of a female Roughhead blenny (Acanthemblemaria aspera), photographed against the blue water, sticking out from its home in a tube on a coral reef. East End,...

Tony Wu / Blenny (Neoclinus monogrammus) female, Shikoku, Japan.

Tony Wu / Blenny (Neoclinus monogrammus) male with his mouth wide open. Kashiwajima, Japan.

Alex Mustard / Secretary blenny (Acanthemblemaria maria) dominant male in hole of Boulder brain coral (Colpophyllia natans) East End, Grand Cayman, Cayman Islands. Caribbean Sea.

Alex Mustard / Portrait of a Secretary blenny (Acanthemblemaria maria) peeking out from its hole in a coral reef. Cayman Brac, Cayman Islands. Caribbean Sea.

Constantinos Petrinos / Striped fangblenny mimic (Petroscirtes breviceps) coming out of a bottle, Lembeh Strait, North Sulawesi, Indonesia.

Constantinos Petrinos / Striped fangblenny mimic (Petroscirtes breviceps) coming out of a bottle, Lembeh Strait, North Sulawesi, Indonesia.

Constantinos Petrinos / Striped fangblenny mimic (Petroscirtes breviceps) coming out of a bottle, Lembeh Strait, North Sulawesi, Indonesia.

Constantinos Petrinos / Striped fangblenny mimic (Petroscirtes breviceps) coming out of a bottle, Lembeh Strait, North Sulawesi, Indonesia.

Constantinos Petrinos / Striped fangblenny mimic (Petroscirtes breviceps) coming out of a bottle, Lembeh Strait, North Sulawesi, Indonesia.

Aflo / Blenny (Neoclinus bryope) peering out of coral with mouth open, Wakayama, Kushimoto, Japan. December.

Pascal Kobeh / Arabian fangblenny (Petroscirtes ancylodon), coast of Dhofar and Hallaniyat islands, Oman. Arabian Sea.

Pascal Kobeh / Arabian fangblenny (Petroscirtes ancylodon), coast of Dhofar and Hallaniyat islands, Oman. Arabian Sea.

Alex Mustard / Shorthead fangblenny (Petroscirtes breviceps) peeking out of the neck of discarded bottle. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Alex Mustard / Panamic barnacle blenny (Acanthemblemaria hancocki). La Paz, Mexico. Sea of Cortez, East Pacitic Ocean.

Alex Mustard / Brown Sabretooth Blenny (Petroscirtes lupus) in a discarded coke can. Sydney harbour, New South Wales, Australia.

Alex Mustard / Secretary blenny (Acanthemblemari maria) yawns as it peers out from a hole in the reef. West Bay, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea.

Alex Mustard / Roughhead blenny (Acanthemblemaria aspera) male portrait. This species is very small, just 20mm long and 1-2mm deep, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Alex Mustard / Roughhead blenny (Acanthemblemaria aspera) high magnification portrait of a golden variety of living in it's tube on a coral reef, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbea...

Alex Mustard / Sailfin blenny (Emblemaria pandionis) male displaying his large dorsal fin, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Norbert Wu / Spotjaw Blenny (Acanthemblemaria rivasi) in Brain Coral, large red eyes scare off predators, Caribbean

Norbert Wu / Bluethroat Pikeblenny (Chaenopsis ocellata) male attacking its mirror image, West Palm Beach, Florida

Norbert Wu / Sailfin Blenny (Emblemaria pandionis) male courting, West Palm Beach, Florida

Alex Mustard / Shorthead sabretooth blenny (Petroscirtes breviceps) emerging from its home in a discarded tin can, Bitung, North Sulawesi, Indonesia, Lembeh Strait.

Alex Mustard / RF - Spinyhead blenny (Acanthemblemaria spinosa) peering out from a hole in a coral reef, surrounded by Brown boring sponge (Cliona sp.) and sponge zoanthids (Parazoanthus parasiticus), Grand Cayman,...

Alex Mustard / Golden roughhead blenny (Acanthemblemaria aspera) peering out from its hole in a coral reef, Grand Cayman, Cayman Islands, Caribbean Sea.

Alex Mustard / Flagfin blenny (Emblemariopsis bahamensis) pair, male black, female visible behind, looking out from nesting hole in a coral reef, Grand Cayman, Cayman Islands, Caribbean Sea.

Alex Mustard / Spinyhead blenny (Acanthemblemaria spinosa) juvenile, looking out from a hole in coral reef, surrounded by brown Boring sponge (Cliona sp.) and Sponge zoanthids (Parazoanthus parasiticus), East End, G...

Alex Mustard / Shorthead sabretooth blenny (Petroscirtes breviceps) emerging from its hole in a piece of bamboo, with diver's lights in background, Bitung, North Sulawesi, Indonesia, Molucca Sea.

Russell Laman / Secretary blenny (Acanthemblemaria maria) hiding underneath a Christmas tree worm (Spirobranchus giganteus) Bonaire, Caribbean.

Alex Mustard / Spinyhead blenny (Acanthemblemaria spinosa) peering out from a hole in coral reef, Grand Cayman, Cayman Islands, Caribbean Sea.

Alex Mustard / A tiny Revillagigedos barnacle-blenny (Acanthemblemaria mangognatha) peeking out from a crevice, Socorro Island, Baja California, Mexico, Pacific Ocean.

David Hall / Male Yellowface pike-blenny (Chaenopsis limbaughi), living in abandoned tubeworm holes in sand, flaring its dorsal fin in threat display, Dominica, Eastern Caribbean.

David Fleetham / Spinyhead blenny (Acanthemblemaria spinosa) peeking out from a hole inhard coral, Bonaire, Lesser Antiles, Caribbean Sea.

Alex Mustard / Portrait of a Secretary blenny (Acanthemblemaria maria), living in a hole in the base of a purple common sea fan, on a coral reef. East End, Grand Cayman, Cayman Islands, British West Indies. Caribbea...

Claudio Contreras / Browncheek blenny (Acanthemblemaria crockeri), San Rafaelito Lighthouse Islet, Balandra National Protected Area, near La Paz, Gulf of California (Sea of Cortez), Mexico, September

Claudio Contreras / Browncheek blenny (Acanthemblemaria crockeri), San Rafaelito Lighthouse Islet, Balandra National Protected Area, near La Paz, Gulf of California (Sea of Cortez), Mexico, September

Tony Wu / Blenny (Neoclinus bryope) male which has an unusual dorsal fin with multiple blue spots. Kanagawa, Japan.

Tony Wu / Blenny (Neoclinus bryope) male, peeking out from the safety of his hole in the reef, on the lookout for eligible females during the winter reproductive season

Tony Wu / Blenny (Neoclinus bryope) male active during the winter reproductive season. Kanagawa, Japan.

Tony Wu / Blenny (Neoclinus bryope) male has just darted out from its hole to scan for passing prey. Kangawa, Japan.

Tony Wu / Blenny (Neoclinus bryope) male has just darted out from its hole to grab a tiny crustacean, which can be seen swimming in front of the blenny. The fish's eyes are focused on its prey. Kangawa, Jap...

Tony Wu / Chaenopsid blenny (Neoclinus bryope) during the winter breeding season, Kanagawa, Japan.

Tony Wu / Pictured here is a pair of Blenny (Neoclinus bryope) the larger male above, smaller female below. The female has just entered his burrow. She will deposit eggs inside. The male will fertilize them and...

Tony Wu / Three male Blennies (Neoclinus bryope) engaged in a stand off during the reproductive season, Kanagawa, Japan.

Magnus Lundgren / Wild Wonders of China / Wolf fangbelly (Petroscirtes lupus) hiding in plastic waste drifting out in the open sea, just below the surface. This is a species of combtooth blenny often found around coral reefs in the western Pa...

Pascal Kobeh / Two sarcastic fringeheads (Neoclinus blanchardi) fighting for their territory. They expand their mouth to impress their opponent. Pacific ocean, California, USA.

Claudio Contreras / Spinyhead blenny (Acanthemblemaria spinosa), Banco Chinchorro Biosphere Reserve, Caribbean region, Mexico.

Alex Mustard / Portrait of a Spinyhead blenny (Acanthemblemaria spinosa) living in a yellow branching tube sponge (Pseudoceratina crassa). Jardines de la Reina, Gardens of the Queen National Park, Cuba. Caribbean Se...

Alex Mustard / Spinyhead blenny (Acanthemblemaria spinosa) looks out from its hole in a Boulder brain coral (Colpophyllia natans). East End, Grad Cayman, Cayman Islands, British West Indies. Caribbean Sea

Claudio Contreras / Spinyhead Blenny (Acanthemblemaria spinosa), Cienaga de Zapata National Park, Matanzas Province, Cuba.

Linda Pitkin / Shorthead sabretooth blenny (Petroscirtes breviceps) inhabiting a discarded sponge-encrusted bottle on the sea bed. Lembeh Strait, North Sulawesi, Indonesia.

Alex Mustard / Portrait of the face of a Spinyhead blenny (Acanthemblemaria spinosa) looking out from its home in a Starlet coral (Siderastrea siderea) on a coral reef. East End, Grand Cayman, Cayman Islands, Britis...