Category: Coral Reef


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   © Oceana.org

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 152

The Veined Octopus or Coconut Octopus is the only invertebrate known to use tools, and one of only two octopuses known to exhibit bipedal behaviour by “walking” on two of its legs.

Coconut octopus in Lembeh   © Marco Carnovale

Originally discovered in 1964, Amphioctopus marginatus lives in the tropical waters of the western Pacific Ocean.
The species is commonly known as Veined Octopus, named after the distinct dark brown lines that branch over the mantle and down the arms of the animal. The edges of their arms are often darkened in contrast to the white-blue suckers.

Coconut Octopus   © franklin tom

Another common name for these molluscs is Coconut Octopus, which relates to a very peculiar and interesting behaviour of the species: it carries coconut shells and clam shells across the ocean floor and uses them to build fortresses.

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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 146

Octopuses have the largest brains of any invertebrate.

Common Octopus   © ARKive

The fact that these creatures, whose ancestors diverged from the lineage that would lead to ours roughly 500 to 700 million years ago, have developed intelligence, emotions, and individual personalities is challenging our understanding of consciousness itself.

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Underwater Fact 138

Larval Clownfish are able to smell their predators.

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Underwater Fact 135

Turritopsis Nutricula is a species of Jellyfish that can age backwards.

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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 129

Giant Clams are colourful creatures that have hundreds of simple eyes along the edges of their mantle.

The Tridacnid’s eyes are visible as dark spots along the mantle

The largest species of Giant Clam, the Tridacna, are the largest bivalves ever to have existed in the fossil record.
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