|
UK Sea Life
| |
Snakelock Anemone (Anemonia viridis) |
|
This anemone cannot withdraw its 200 or so tentacles
so they constantly writhe about in the current searching for food.
They are mostly olive brown and apple green, some have purple tips
to their tentacles where the greatest number of stinging cells
can be found.. |
Dalia Anemone (Urticina felina) |
|
The Dalia gets its name from the similar Dalia flower. The
short, stubby tentacles and mouth disc are patterned with bands
of colour ranging from blues and greens to pinks and reds. A strong,
sucker-like base ensures firm attachment to the rock, even in the
most wave-swept sites. The column is often covered with warts to
which bits of shell and gravel stick, providing a good disguise
when the tentacles are drawn inside. They can grow up to about
8 inches across. |
Plumrose Anemone (Metridium senile) |
|
Plumrose anemones are usually coloured white or orange,
occasionally buff, yellow or reddish. They grow to about 12 inches
high
They are usually attached to rocks, typically in places
where there is strong current often on projecting substrates
such as piers, sewage pipes and wrecks. |
| This
group of animals is probably best-known for their hard outer
shell. As the animal grows, this shell must be removed and discarded.
Once this takes place, the new shell takes time to harden. During
this period, the animal is without its primary means of protection
and vulnerable to attack from predators. But they have an impressive
arsenal of weapons at their disposal. The claw of many crustaceans
is capable of exerting hundreds of pounds of pressure. But
in spite of their impressive armour and fierce weaponry, the
crustaceans do occasionally meet their match. The beak of the
octopus can crack through the toughest shells of crabs and lobsters,
making an enjoyable meal. |
Spider Crab (Libinia emarginata) |
|
Its carapace grows up to 8 inches across and its
spiny back is often covered with a garden of sponge and seaweed
which the crab plants there for camouflage and which it carefully
transfers to its new shell after moulting. It lives on sand and
amongst rocks down to about 50 metres but comes inshore in large
numbers in the summer to moult and mate, forming huge writhing
mounds of crabs and empty shells as it does so.
Similarly to most crabs, they can only mate shortly after
moulting. Females carry the fertilised eggs in a cavity just
beneath their abdomen.
|
Edible Crab (Cancer paygurus) |
|
Easily identified due to the
pie crust carapace and the black tipped claws. They can grow
to 12 inches across and weigh as much as 5kgs. You will normally
see them wedged into a crack in the rocks or partially buried
in sand. The large claws are very strong and can easily crack
open oyster or mussel shells.
Crabs
mature at the age of five, and usually spawn every other
year. The females carry their eggs under her flap in winter,
until they are ready to hatch in early summer. Females
have a broader posterior flap underneath than the males,
and is how one tells them apart. |
Hermit Crab (Pagurus bernhardus) |
|
Hermit crabs are crustaceans that are adapted to
live in empty shells. They have a long soft abdomen which is curved
to fit into the spiral of the shell and their two claws are often
different sizes.
The shell protects the hermit crab from predators. The crabs
carry their shell around and it acts as a 'portable burrow'
but they can easily move out of their old shell and into a
new one. It is very important that the shell fits well, If
it is too small it will not protect them and if it is too large
they waste energy carrying it around.
Before moving out of their old shell and into a new one a
hermit crab spends a long time investigating the new shell
and comparing it to their old one. They might turn the shell
over several times and run their claws over the outside of
the shell to check that it is not damaged. They then insert
their claws into the shell to gauge how much space is inside
it. Even after they have moved into the new shell they often
investigate their old shell one last time before finally deciding
which one to occupy.
Sea anemones often attach themselves to the shell and give
added protection with their stinging tentacles - when the crab
changes its shell it prises off the anemones and puts them
on the new shell. |
Velvet Swimming Crab (Necora puber) |
|
A fast moving and aggressive swimming crab, blue
in colour but obscured by a brown pubescence with red prominences.
The dorsal surface has a finely velvety texture and the eyes are
red. It grows to about 8 cm. The hind legs are flattened to assist
in swimming although this is rarely seen.
Also known as the fiddler crab. |
| These are simple animals, lacking a
brain and complex sensing organs. Echinoderms are characterized
by their radial symmetry and a central mouth. Although a sea urchin
looks round, closer inspection reveals that it is nothing more
than a starfish with its legs wrapped inwards to form a sphere.
The echinoderms are found in a stunning variety of shapes and colours,
and are found decorating reefs around the world.
Some of these animals are carnivorous, feeding on corals and
scavenging the ocean floor. Certain species of starfish actually
extend their stomachs into their unwary victims in order to
digest them. The feather stars and sea cucumbers are mainly
filter feeders, catching what ever they can find floating in
the ocean currents. All of the echinoderms move around with
the use of thousands of tiny tube feet, many of which have
suction cups on the ends. Many of the urchins have developed
extremely sharp spines as a means of protection.
|
Sunstar (Crossaster papposus) |
|
These are easily recognisable and have between 8
and 14 arms. Topside they have nobbly spines and concentric coloured
bands, on the underside they are white. They primarily eat other
starfish but have been seen to eat shellfish and even urchins.
They grow to about 10 inches across. |
Common Starfish (Asterias rubens) |
|
Starfish are unmistakable with their five arms with
rows of tube feet on the underside. The central mouth of the starfish
is underneath the upper body. The common starfish is orange in
colour and is occasionally seen with missing arms.
They prey on bivalve molluscs by forcing their shells open
with their tube-feet. The stomach everts over or into the prey
liquefying it so that it can be easily digested. In shallow
waters dense congregations of starfish can be found over an
expanse of several kilometres.
Starfish are propelled very slowly along the sea floor by
their tiny tube feet. Tube feet can produce strong suction,
fixing the starfish in place and making it difficult for a
predator to eat the entire organism. Occasionally starfish
can be seen with missing limbs. This is not a great loss for
a starfish as they can grow them back. Sometimes common starfish
with six or more limbs are seen, this may be a result of the
starfish accidentally growing two limbs to replace a single
loss.
Females release their eggs into the sea and the males respond
to this by releasing sperm into the sea. Fertilisation happens
externally. A single female is capable of releasing up to 2.5
million eggs. Fertilised eggs develop into larvae which are
able to swim about. These larvae swim for about three weeks
before settling and beginning metamorphosis into the more familiar
and sedentary starfish. |
| There are seven species of British wrasse
- which include the Ballan, cuckoo, corkwing, rainbow, scale-eyed,
rock cook and goldsinny. As in all wrasses colouration varies
with age and sex; females and immature males tend to be yellowish
brown to coral pink with a distinctive row of black and white blotches
along the posterior section of the dorsal fin, and with blue edging
to the fins.
They tend to live in areas where there is plenty of weed and
plenty of hiding places. They have sharp spines on their
dorsal fin making them difficult to swallow, both for diving
birds like cormorants and predatory fish such as bass.
Wrasse have strong teeth, both in the jaws (for biting and rasping)
and on the pharyngeal bones in the throat (for gripping and crushing)
for eating molluscs and crustaceans. These are slow-growing fish,
and males can live for more than twenty years; they attain a
length of typically 12 inches when fully grown. |
Cuckoo Wrasse |
|
This wrasse has lovely colouring making it one of the prettiest
fish in the UK.
As with Ballan wrasse, the cuckoo wrasse start life as females.
The gaudy male usually has a harem of several females and if
he dies one of them will change sex to replace him.
|
Ballan Wrasse |
|
|
The ballan wrasse is native to British waters and found all around
our coasts. - and grows to a weight in excess of ten pounds. It
is found in all rocky areas, where it lives amongst the kelp and
other seaweeds found on the ocean floor. They sleep through the
night.
The ballan wrasse eats many of the creatures found amongst
such rocky locations, but tends not to eat other fish. Most
of the time it will eat shrimps, prawns, crabs and shellfish,
with its powerful jaws and blunt, poker-like teeth. It is quite
capable of plucking a limpet from the rocks and then demolishing
it. Ballan wrasse have a second set of teeth in their throat. |
Lobster (Homarus gammarus)
|
The lobster is well-known for its gastronomical
qualities. The largest specimens reach a size of 2 feet (60 cm)
and a weight of 6 kg, but in general they are mostly about 1.5
feet (50 cm). The claws are enormous, especially in
the adult males and end in strong grips, slightly asymmetrical.
One of the claws is broader and armed with serrated cutting
edges (crushing grip), the other thinner and is armed with a line
of teeth on the internal edge of the fixed finger (cutting pliers). The
general colour of the body is blue dark and marbled and the
antennas are oranges.
The lobster is omnivorous and consumes any animal, which it
is able to catch; generally they are slow animals like molluscs,
worms, and Echinoderms. Occasionally it also attacks with
other shellfish and fish, and also nourishes on dead animals
and algae.
The lobster spends the day in its shelter, which it constantly
alters by pushing the sediments towards outside with its grips.
The shelter is generally a natural crack according to the size
of the animal, and possibly modified by digging. You can sometimes
see the displaced stones etc on the outside of its den. At
night, the lobster leaves its shelter to seek its food, which
it detects mainly through smell.
It is about a rather aggressive animal, which attacks
any animal that is smaller than itself. Large males often show
a marked territorial behaviour i.e., defence of the shelters,
territories, battles for females etc. In certain areas the lobsters
carry out small seasonal migrations.
Mating occurs just after the moult of the female. Sperm is introduced
by the abdominal appendices of the male and the female can store
it so the female can fertilize its eggs with the same for at
least two years. The eggs (5000 to 50.000 according to the size
of the female) are laid from July to December, and are carried
attached to abdominal appendices of the females for 7 to
10 months, hatching May - June time. On average the lobster moults
ten time the first year, 3 to 4 times the second, 1 to 2 the
third, 1 only time then, and after less and less frequently until
complete stop of the growth. |
Dead Mens Fingers (alcyonium digitatum)
|
This soft coral can grow to about 10 inches long and come in
a range of colours such as white cream, grey, pink and orange,
the polyps are translucent white. These were photographed in the
Farne Islands where the whole uneven terrain is covered in them,
a spectacular sight. |
Conger Eel (conger conger)
|
The conger is found on rocky and sandy bottoms. It stays near
the coast when young and moves toward deeper waters upon reaching
adulthood . It is mostly nocturnal, hunting at night and resting
in crevices during the day . It feed on fish, crustaceans,
and cephalopods. It grows rapidly and can weigh as much as 40 kgs
by it 5th year.
It becomes sexually mature at an age of 5-15 years and like
other species of the group, it reproduces only once in its life
but lays 3-8 million eggs. As they come into breeding condition
a number of radical changes take place, they stop feeding and
loose their teeth and gut, and other organs start to degenerate
and the skeleton starts to decalcify. At the same time the gonads
increase in size and fill the whole body cavity. They effectively
become a huge sperm or egg case. The Eels then all swim to somewhere
near Gibraltar and at a depth of about 2000-4000m they spawn
in the summer and die. The fertilised eggs drift in the
currents. |
Lessor spotted Dogfish (Scyliorhinus canicula)
|
Dogfish are small sharks and have many shark-like features such
as low-slung mouths, hydroplane-like pectoral fins and uncovered
gill slits. The species most often seen by British divers is the
lesser spotted dogfish. It is also known as the rough hound
and in fish shops has the more appetising name of "rock salmon".
They are often seen sleeping on the seabed during the day as they
feed at night. They are indiscriminate hunters and munch on crabs
and whelks as well as eating bottom-living fish like gobies, dabs
and gurnards. They will also hunt shoaling fish such as herring
and pilchards.
Dogfish scales are formed like teeth. If stroked nose
to tail, a dogfish feels quite smooth but in the opposite direction,
decidedly rough.
Dogfish rely heavily on their sense of smell when hunting and
have been observed slavishly following a scent trail similarly
to a bloodhound. They are also able to detect faint electrical
fields produced by the muscles of hidden prey.
 Most
fish simply eject eggs and sperm into the water near each other
and hope they meet method. Lesser-spotted dogfish, however, use
internal fertilisation, a much more intimate approach. The male
wraps his body, in the shape of a ring, around the female. He
inserts the sperm with specially adapted pelvic fins known as "claspers".
Dogfish egg capsules are light brown and almost see through (especially
if held against a torch) are known as mermaids' purses (right)
and have long tendrils on the corners. The female swims round
and round a clump of seaweed as she lays, so that the eggs become
well anchored. The young dogfish emerge around 9 months later
as fully-formed miniature adults about 4 inches long. |
|
|
