The Caribbean Monk Seal and the the Icthyosaurus are two modern sea creatures that are currently extinct but there have been many more in prehistoric times.
No it is not but it is a very rare sea creature.
The sea mink became extinct because is was hunted to extinction for it's fur.
There are lots of animal that are extinct, but can you be more specific? Like a name?
Extinct Steller's Sea Cow Bhaji River Dolphin Endangered Sea Otter Manatee
The Woolly mammoth is extinct (dead). When it was alive it was the biggest land animal but there were bigger animals in the sea.
Manatee
definitely walruses and sea lions... they are killed for there fat and carcases.
Pollution, strictly plastic bags. Leatherback sea turtles are the only animal that eats jellyfish. If this animal goes extinct, jellyfish will multiply rapidly.
you can't have an extinct animal living. It can be endangered or close to being extinct, but not extinct.
Leafy Sea Dragon is an animal, a dragon who lives by the sea- where the name comes from.
Thylacine and Dodo. If you mean "Extincis" to be "extinct."
First of all, what animal is it? But anyway whatever animal it is, people are shooting it or killing it. If its a water animal that lives in the ocean, maybe the pollution in the sea or lake is floating and they think it is a play toy and they eat it. Its hard to explain if you don't have what kind of animal it is. Really everthing is going extinct in this world.