Category: Fish

Underwater Fact 157

The Longhorn Cowfish (Lactoria cornuta), also called the Horned Boxfish, is easily recognised by the two long horns on its head and it’s bright yellow body.

Longhorn Cowfish   © Aqua Marine Life

The eyes of the Longhorn Cowfish move independently from each other, so these animals are able to look in two different directions at the same time.

This slow-moving and generally peaceful species has poisonous skin and if threatened or stressed they can release a toxin into the water that may be lethal to other boxfish and various other organisms.

Boxfish Skeleton   © UC San Diego

Interestingly, the cowfish does not have an internal skeleton like other bony fish, but rather a rigid, hard carapace of fused scales from which the horns, fins, eyes, and lips protrude. This hard, shell-like body looks more like the exoskeleton of crustaceans and similarly functions as protection against predators.

Underwater Fact 155

During its lifespan, the beautifully coloured parrotfish is known to change its shape, colour and even gender.

Parrotfish sleeping   © Nikki van Veelen

Parrotfish are abundant in and around the tropical reefs of all the world’s oceans. There are about 80 identified species, ranging in size from less than 30 to 120 cm (1 to 4 ft) in length. All species vary in their colour and shape and each fish repeatedly changes throughout their lives, making it difficult for researchers to identify and classify the individuals.
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Underwater Fact 153

Despite its name the ‘Common Skate’ is nowadays extremely rare.

Common SkateCommon Skate   ©

Skates are found in most parts of the world, from the shallow waters on the coast to depths of 2700 metres. They are flattened fish that look very similar to their well-known relatives: the rays.
The major difference between rays and skates is their reproductive strategy. Rays are live bearing (viviparous) while skates are egg-laying (oviparous).

The Common Skate or Blue Skate (Dipturus batis) is the largest skate in the world attaining a length of more than 250cm.
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Underwater Fact 151

Spiny Gurnards feature large colourful fins and venomous spines that help searching for food.

Eastern Spiny GuarnardEastern Spiny Gurnard   © Klaus Stiefel

Gurnards, also called Sea Robins, are recognised by their beautiful large pectoral fins which they flap like wings, opening and closing them while swimming. This colourful display is mainly intended to distract predators.
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Underwater Fact 150

Lionfish are venomous, not poisonous – there is a difference.

Pterois640Lionfish   © Sophia Volzke

Although both venomous and poisonous animals produce a toxin that can be harmful to other organisms, the method of delivery is different. Venomous organisms use a specific apparatus like spines or teeth to inject their toxin. Poisonous organisms, on the other hand, require their victim to ingest or absorb the toxin.

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Underwater Fact 145

Cownose Rays are known to take on long migrations in schools of thousands of individuals, moving northwards in late Spring and southwards in late Autumn. It is believed that this migration is initiated by the orientation of the sun and by water temperature.

 01-Cownose Rays migration, Gulf of MexicoCownose Rays migration, Gulf of Mexico   © Sandra Critelli

Cownose Rays can be recognised by their unusual bi-lobed head. Under the snout are two large fleshy lobes. These are often mistaken as the entrance to the mouth. The mouth however, is on the underside the fish.

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Underwater Fact 142

Manta rays have the largest brain to body weight ratio of any living fish.

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Underwater Fact 138

Larval Clownfish are able to smell their predators.

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Underwater Fact 134

Seahorses have a 90 percent success rate when attacking prey, which makes them one of the most successful predators in the ocean.

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Underwater Fact 133

Sand Tiger Sharks are the only sharks known to come to the surface and gulp air. They store the air in their stomachs, which allows them to float motionless in the water while hunting.

Sand Tiger Shark   © Mark Fox

This Shark is not related to the Tiger Shark (Galeocerdo cuvier) however, it is a cousin of the Great White Shark (Carcharodon carcharias).
Despite its fearsome appearance and strong swimming ability, it is a relatively docile and slow-moving shark that will only attack a human when threatened.

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