If you think about the marine food chain you can work this out.
The basic food in the sea is provided by the phytoplankton (single celled plants the float about in the top layers of the oceans). This is eaten by zoo plankton which are very small animals that also float about near the sea surface (except that they swim up at night and down during the day) - everything else living in and from the sea feeds on the zoo plankton or on animals that eat the zoo plankton.
Thus as creatures are animals the most common creatures in the sea and thus the most common sea creature in the world is the zoo plankton.
yes it is
no but it can swim out to sea, try google
A sea dollar R
The monstrous biblical sea creature is commonly referred to as Leviathan in the Bible. It is described as a large and powerful creature that symbolizes chaos and evil in some biblical texts.
The box jellyfish is considered one of the most poisonous creatures on Earth. Its venom can cause a very painful and potentially deadly sting to humans if you encounter one. However, it's important to note that "most poisonous" can vary depending on factors such as delivery method and toxicity level.
A dorado
sharks
tiger shark
most do but some maynot
Piranna
KOMODO dragon
A Great White shark
certain species of sea snake
The most dangerous deep sea creature is the Sea Wasp. A deadly jellyfish. The slightest touch of their tentacles creates a permanent rash and horrible pain. Any harder and your toast.
dolphins
single unicellular creature
a Caribbean sea creature