Wednesday, 21 February 2018


The Grunion Fish from California synchronise their breeding cycle with the spring tides.
At the peak of a spring tide large numbers of Grunion deliberately strand themselves on the shore. The females bury their tails in the sand and lay their eggs. The males are entwined around them and release sperm to fertilise the eggs. The fish then propel themselves backwards to catch a wave to carry them back into the ocean. On the next spring tide (about 15 days later) the eggs hatch and the babies swim off in the high tide.

Wednesday, 14 February 2018

Image result for eel fish


Some fish are able to sense their surroundings by changes in an electric field generated around them by modified muscle cells. The changes are picked up by sensors along the fish's body. The nature of these changes depends on how well objects conduct electricity..
Some fish also use electricity to stun their prey. Some electric eels generate up to 550 volts.

Thursday, 18 January 2018

Staying Afloat

The group of fish which evolved with bony skeletons also evolved a way of staying afloat without the constant need to keep swimming.

They developed a swim bladder which is a bag of air that can be filled or emptied by diffusion of gases or by expelling the gases direct 

This way a fish can control its buoyancy and level in the water.

Compare a picture of a shark and a fish.

What other differences might help to make the fish such a manoeuvrable swimmer? 

Tuesday, 9 January 2018


Did you know a charging shark cannot stop. It can swerve but it can't swim in reverse. If it stops beating its tail it sinks.

Rays and skates, which have skeletons made of cartilage the same as sharks, have given up on the energy consuming task of constantly beating their tails. They have become bottom, dwellers. Their tails have become thin and whip like and some have developed poisonous barbs on the end

Tuesday, 19 December 2017

Back To The Future

In the movie Jurassic Park, scientists were able to breed dinosaurs using the DNA extracted from mosquitos trapped in amber. In reality the only DNA  would have been from the mosquito!

However, scientists have used chicken DNA to breed chickens with primitive characteristics like teeth. Did you remember that birds evolved from dinosaurs?

By 'switching on' inactive parts of the chickens DNA scientists may be able to breed chickens with dinosaur characteristics

Tuesday, 12 December 2017

Did You Know ... ?

The Cusk Eel is found 8.4 kms beneath the ocean's surface.

What would conditions be like for them ?
  • The high pressure would be a  problem
  • It's too deep for sunlight to reach.
  • It's very cold - about 1d Celsius 
 Giant Cusk Eel

Tuesday, 5 December 2017

Do Fish Mix With Other Fish? - Kim

Dear Kim,
Mostly fish hang with their own species, it's safer that way!
The bigger sarcopterygians could make a meal of the smaller species.