Fish

Overview

Fish are cold blooded with a streamlined shape and bilateral symmetry, meaning the left and right sides are identical. Fish can be divided into three groups including Bony fish (Osteichthyes), most saltwater & freshwater fish; Cartilaginous fish (Chondrichthyes), sharks, skates and rays; and Jawless Fish (Agnatha), lampreys and hagfish.

As a general rule, the body of a fish is streamlined and covered in a series of protective scales. Fish have a wide variety of body forms to suit the diverse environments they inhabit. Fins are generally used by fish for propulsion and steering. The surface of a fish is usually covered in a layer of thin overlapping bony plates called scales. These act as protective armour and are covered in slime secreted by the skin to protect the fish against disease and parasites. As a general rule, the body of a fish is streamlined and covered in a series of protective scales. Fish have a wide variety of body forms to suit the diverse environments they inhabit. Fins are generally used by fish for propulsion and steering. The surface of a fish is usually covered in a layer of thin overlapping bony plates called scales. These act as protective armour and are covered in slime secreted by the skin to protect the fish against disease and parasites. The bone structure of fish is similar to that of other vertebrates and, like all vertebrates, they require oxygen to survive. Unlike their mammal relatives, they do not breathe air. Instead, they absorb oxygen directly from the water through their gills, which are made up of layer upon layer of lamellae. These are a collection of 'thin plates' containing a rich supply of blood vessels which together form a comb-like structure. Due to their layered arrangement, the gills provide the fish with an incredibly vast surface area for respiration.

Sharks, rays and skates have a skeleton made of cartilage, not bone. Despite their reputation for being dangerous, most species are harmless and docile animals. Only ten out of approximately 360 species of sharks are considered dangerous. Over 200 million sharks are killed annually through the commercial and recreational fishing industry, and pollution. Shark finning contributes to this death rate and involves the removal of the fins from the shark before discarding the remainder of the body alive. The fins have a very high market value in comparison to the flesh, therefore leading to the non-utilisation of the whole animal. Sharks are one of the ocean's largest predator groups and an essential element to the marine food chain. Their demise would be extremely detrimental to the marine ecosystem, and in turn our commercial fisheries.

Rays, like sharks, are a member of the cartilaginous group of fish, so called because their skeletons are made of cartilage instead of bones. Rays' gills lie on the underside of the body. Instead of taking in water through their mouths like sharks, rays take it in through two openings, called spiracles, on the top of their head behind the eyes. Each spiracle is fitted with a special valve which is shut when the ray breathes out. Rays swim by using a flapping motion with the edges of their body (the pectoral fins). Of the 75 species of ray, approximately 30 are stingrays. Stingrays have barbs at the base of their tail, but these are only used as a last resort defence mechanism when they are threatened.

How many people die from shark bites per year?

Last year, worldwide, 3 people died due to shark attacks, in comparison, 150 people died from coconut strikes, 200 people died from elephants, and 2 million people died from not washing their hands and contracting bacterial diseases.

What is an interesting fact about sharks?

A shark cannot stop moving suddenly and can not swim backwards.

How did the Grey Carpet shark get its name?

A Grey carpet shark can rest on the bottom of the ocean in large numbers for hours. Hence the name as they look like a grey piece of carpet on the ocean floor.

Are Leopard and Zebra sharks the same?

Yes, when a Leopard shark is born they have light and dark brown stripes like a zebra, however it loses them with age and get spots instead, hence the name Leopard shark. In America they are known as a Zebra shark because they are born with the spots.

What is the value of Sharks in our Marine Ecosystem?

Sharks play an important part in the marine ecosystem and are a valuable resource in our oceans. They provide enjoyment and education through shark viewing and diving excursions, recreational and commercial fishing, medical research and they are vital in maintaining ecology in the ocean through their role as an apex predator in the food chain. But shark populations are decreasing and many species are close to becoming endangered as a direct result of human activities. Overfishing, habitat destruction, finning, destructive fishing methods such as netting and trawling, and pollution are major threats to shark populations worldwide.

History reflects a turbulent relationship between man and sharks - one of the world’s greatest predators. Sea Worlds latest exhibit Shark Bay will reveal a new dimension of understanding and will unravel the mystery and misconception surrounding this majestic marine species. Complementing this very important educational role will be the exhibit’s use as a major facility to undertake non-invasive research, which will ultimately assist with the preservation of sharks in the world’s oceans. Shark Bay will play a major role in contributing to the understanding and appreciation of the Shark species and their environment.

In Australia commercial and recreational fishing kills up to 440 Great White sharks per year.

There are less than 500 individual Grey Nurse sharks on the East Coast of Australia.