SHARK BIOLOGY
WILD STORIES: GREAT WHITE
SHARK BIOLOGY
What are the key features of a shark and how are they grouped?
How do they sense the world around them? From reproduction to adaptations, sharks are a diverse and fascinating group.
SHARK SKOOL
WILD STORIES: GREAT WHITE
SHARK BIOLOGY
Fun free activities to download - ideal projects at home or school. Includes model making, puzzles and colouring pages
WILD STORIES: GREAT WHITE
WILD STORIES: GREAT WHITE
WILD STORIES: GREAT WHITE
Take an incredible journey with a great white shark and see the dangers she faces on the way. Based on real science, we see remarkable encounters with other marine species
ANATOMY & BEHAVIOUR
ANATOMY & BEHAVIOUR
ANATOMY & BEHAVIOUR
REPRODUCTION
ANATOMY & BEHAVIOUR
ANATOMY & BEHAVIOUR
FACT FILES
ANATOMY & BEHAVIOUR
FACT FILES
Sharks are just one part of the elasmobranchs - these fish all have a cartilaginous skeleton. This simply means their bones are flexible and as such, offer additional flexibility.
The rays and primitive chimeras (e.g. the spotted ratfish) are related to the sharks, although there are key features that make them distinct...
- 5 - 7 gill slits
- Pectoral fins that are not part of their heads
Despite having a diverse range of shapes and sizes, the sharks all have a similar body plan.
The cartilaginous skeleton means the fins are far more rigid than other fish. The shape of their fins tells you a great deal about the lifestyle of the shark (see the Shark Skool "Fin-tastic Fins" activity).
The differences in their physical features allows scientists to further split the "shark family" in to orders...
SHARK SENSES
TASTE
ELECTRORECEPTION
TASTE
Sharks lack a mobile tongue but are able to distinguish taste in their mouths and as such, they can determine if they like or dislike, the taste of items in their mouths.
SMELL
ELECTRORECEPTION
TASTE
Hundreds of times more sensitive than our own sense of smell, sharks can detect minute traces of chemicals in their environment. Their nostrils, or nares, don't connect to their throats.
ELECTRORECEPTION
ELECTRORECEPTION
ELECTRORECEPTION
Small pores on the faces of sharks known as ampullae of Lorenzini detect electrical impulses created by the muscles of their prey, which may be hidden.
VIBRATIONS
VIBRATIONS
ELECTRORECEPTION
A series of sense organs along the length of sharks, known as the LATERAL LINE detects vibrations created by other animals as well as giving the shark feedback about it's suuroundings.
TOUCH
VIBRATIONS
HEARING
Just like ourselves, shark skin is sensitive to touch, although some have specific sensory organs known as BARBELS that probe in the seabed to find where food may be hidden.
HEARING
VIBRATIONS
HEARING
Sharks have an incredible sense of hearing and they are able to hear some noises from from many miles away. They are highly sensitive to low frequencies as this suggests the presence of injured/ distress fish.
SHARK SIGHT
Shark eyesight is actually rather good. They don't see the full range of colours that human do, but their night vision is far better, thanks to a tapetum lucidum (a reflective layer within the eye that amplifies the available light).
Given the importance of vision, sharks protect their eyes by either "rolling" them backwards to avoid injury (this makes them appear to turn white e.g. great white sharks) or they have a transparent nictitating membrane, which acts rather like a shield and avoids damage to the sensitive eye surface.
Great whites have been seen peering above the water surface in a behaviour called "spy-hopping". This allows them to assess signs of potential prey.
Mutualism
Mutualism, or symbiosis, is a mutually beneficial relationship between two species. Many sharks gain from the cleaning services of various fish who make remove parasites, dead skin or debris that may collect around teeth and gills.
Such fish that you may assume could be an easy meal are tolerated and the sharks present no risk to them, given their positive health benefits.
Probably the most well known of these are the striped pilot fish and the remora which cling to the shark with a "sucker" pad on their heads.
These fish also get extra food from the small pieces that come away from the shark feeding.
LIFE ON THE SEABED
There are often clues that a shark has a lifestyle associated with the seabed. Often the upper lobe of the tail is much longer and they are more flattened on their underside. Some may have elaborate camouflage (e.g. wobbegong) or sensitive, moustache-like, organs called "barbels" that seek out possible prey in the sea floor.
Other species may go further still. The angel shark is flattened so extremely, it resembles the closely related rays. Here they wait for prey to pass and undertake an explosive ambush.
DENTAL DETAILS
Tooth shape is highly indicative of the sharks diet. Some fish eating species specialists (e.g. mako) have curved, hook-like teeth ideal for piercing and holding on to slippery prey. The shellfish-eating horn sharks (e.g. Port Jackson shark) have teeth fashioned as crushing plates like a pestle and mortar that break about the hard exteriors of their prey.
A saw-like, serrated edge is ideal for tearing away flesh and is seen in the triangular, blade-like dentition of great white sharks. As tiger sharks diet is so diverse, they have adapted a dental design that distributes force across the tooth, allowing it to break into prey such as turtle shells whilst equally being as effective in tearing apart marine mammals, fish and even other shark species.
MARVELLOUS MARKINGS
Why do sharks display such varied markings?
The leopard shark is at risk of becoming prey to larger species and so their skin patterns, with light and dark patches break-up their shape in the dappled light of the kelp forest habitat.
With their camouflaged colouration and large rosettes decoration (and not least their stealthy hunting), there is a justified connection with their big cat namesakes. There are a number of "spotted" sharks, that actually look very different .
CHANGING COLOURS
In order to prevent zebra sharks competing with immature sharks, and so preventing them being chased away, the pups emerge with a distinct black and white banded pattern. As the juveniles grow in to adults, this changes to the a yellow, spotted colouration.
Another example of a changing appearance is that of the tiger shark, whose pups show a spotted skin that becomes the distinctive stripes that give this shark their name.
INDENTIFYING INDIVIDUALS
Whale sharks have an elaborate pattern over their skin. This not only helps them distinguish between sexes and one another, but such is the uniqueness of the patterns that scientists can use these patterns to recognise individuals.
An added advantage is that the shark is less likely to be seen as it approached balls of fish with the dappled light blending in with the white patches over their back.
COUNTERSHADING
There is a very good reason why many marine animals (from orca to penguins and many sharks) have a pale underside and darker-coloured back. This is called counter-shading and has the double advantage of making the shark hard to see when looking down in to the darker depths and is equally well hidden when looking up at the lighter surface waters.
SHARK REPRODUCTION
Shark reproduction is very bizarre and not only do sharks have three utterly different approaches to having young, the number of offspring, known as pups, varies wildly between species.
As the table demonstrates, the litter sizes range from a handful to hundreds!
All sharks share a method of internal fertilization, with the male using modified pelvic fins (claspers) when mating.
One aspect to consider with shark reproduction is that often sharks take, relative to other fish, a very long time to reach maturity and, whilst there are some large litters, populations take a long time to recover from overfishing or other pressures.
Oviparity is seen in some species with the female laying eggs outside of her body. These have a leathery egg case (often seen on beaches washed up - known as "mermaid's purses").
Sometimes these eggs have strands that tangle in the seabed vegetation, in other cases, the egg is wedged in crevices (they may have projections that help secure the egg in place.
Just like any egg, the embryo relies on a yolk sac to nourish the pup until it is big enough to emerge.
Another method is employed by ovoviviparous species; instead of leaving the eggs to grow and face the dangers of the outside world, the female sharks retain the eggs inside their body.
Not all the eggs grow and these are eaten by the developing young inside the uterus (this is called "oophagy").
In some cases, the young may even devour their siblings - known as inter-uterine cannibalism.
This strategy allows the young to be born at a greater size and potentially have a greater chance of survival.
Viviparous species of shark also grow their pups within the female, but rather then feeding on eggs or siblings, they are linked to their mother's blood system through a special organ called a placenta. The placenta (just like in humans) carries oxygen and nutrients via an umbilical cord which is sited low on their abdomen, between the pelvic fins.
WELCOME TO SHARK SKOOL!
SHARK SKOOL ACTIVITIES
SHARK SKOOL ACTIVITIES
SHARK SKOOL ACTIVITIES
We'll be adding to these easy free and fun learning activities - includes shark model making, colouring pages and word games!
MORE TO BE ADDED SOON!
SHARK GLOSSARY
SHARK SKOOL ACTIVITIES
SHARK SKOOL ACTIVITIES
Learn some scientific shark vocabulary with our A-Z shark glossary. You'll be inspiring your friends with some serious shark knowledge!
20 SHARK QUESTIONS
SHARK SKOOL ACTIVITIES
20 SHARK QUESTIONS
Think you know sharks? See how many of the questions you already know, and boost your shark smarts - more to be added very soon!