The devonian period was as long as 410 to 360 mya it was so long ago that fish rule the seas reptiles did not even evolve yet! In the devonian the first sharks have apeared the sharks nickname was an ironing table because males had the dorsal fin shaped like one.          But this paticular shark was not yet ruling the seas, in                                                                                        
fact there was a much bigger preadator. That mysterios predator that Iam going to tell you in a sec is from the head plated family, does not have real teeth, is a canibal, eats everything he personaly thinks is alive is...
Dunkleosteus, Its so giant it weighs almost 4 tonnes and long up to 10.6 meters but I think it should be miles.
At that time it was known to humans that there was a big population of fish at the devonian which included the big predators such as Dunkleosteus And the shark.

History of animals 1 The Cambrian MYA

 It is really hard to beilive that when first earth formed which was 4.6 billion years ago gained life a few million years after that. The first life visable to human eye was starfishes and jellyfish very very simple organisms.The first fish evolved somewhere between the cambrian and the devonian period. It was so much time ago that not even plants evolved yet, and the oxygen precentage was lower than before. If you go back to the cambrian period you would see a lot of dead bodies on the sea shore because there are just no scavengers to pick on them. One of the giants of that period was the orthocone a giant sea monster that hunted sea scorpians. Imagen you had no eyes and you can only find were light is, and you have a wonderful sense of smell. HOW would you live what would you do? Orthocone does not really relyed on his sight in fact eyes were just forming on the earth. The orthocone used to smell prey and that is how it hunted.

Megalodon

Megalodon is the biggest fish that that has ever lived on the planet earth. Megalodon is 3 times bigger than the great white shark. Megalodon is grey on top and white on the bottom which helps because when prey looks from bottom the belly shows the same color as the sun on top. When looked from top grey looks like the murky water. Megalodon mostly preyed on cetaceans such as cetotherium and squalodon, for adult megalodon and Odobenocetops as a baby. Baby Megalodons live in a habitat which contains a lot of seweed and weed which the Odobenocetops is hunted by the megalodon juvenaels. Adult megalodon hunt in the open ocean so they wont eat their babies because megalodon are canibals.

Harbour Porpoise

The harbour porpoise (Phocoena phocoena) is one of the commonly seen porpoise for crusers and fishers. It is smaller than an adult human men. Most of the porpoises body is grey but some places are black and white. As a baby like most babies it is very playful even to humans. For example there is an aquarium and we have two harbour porpoises there they were both rescued at the same age but not at the same toime, so when the first porpoise her name is daisy,arived she was 2 months old she did not know how to swim so they had to teach her how to do everything for survival. And so after they taght everything to daisy she did not have a pod so they decided to keep her, at the first year of her life she was very playful with people but then Jack got rescued and Daisy stoped playng with people bu stay in the corner away but Jack as a new member he is vey playful. so that is a little story!

Porpoises

Porpoises are sea mamals that are usually recognized as a baby dolphin but it is not. The differences between a dolphin and a porpoise is a pospoise has a more dull like shaped head and and a smaller dorsal fin the side fins and the flukes. Porpoises live in all oceans but only along the coast, because porpoises are smaller so they lose more heat than other marine mammals do so they try to stay in the warmest part of the ocean In the front of the dolphins head there is a melon which produces sound that the dolphin makes. If you look genetically than porpoises are more related to a beluga (the only white whale) than to dolphins. Porpoises are not as playful like dolphins are all they do is they hunt mostly the only time you see them is when they aretaking a breath and not even for long.