Earth's oceans are some of the least explored parts of our planet...it can get really deep and dark down there! One thing we do know about the depths of our oceans, is that creatures can get really BIG! If you've ever heard of the colossal squid than you already know about one of these aquatic beasts...but what makes these animals get so large? Does it have a similar reason to Island Gigantism?
Well when animals grow to large sizes underwater, it's called Deep Sea Gigantism, and although it can occur with many deep sea creatures, it most often happens with invertebrates. For most crustaceans, this occurs because decreasing temperature connects with an increase in size. And at the deepest depths of the ocean, the lack of sunlight definitely keeps it really cold! It is believed that this decreased temperature results in larger cells and a longer lifespan, both of those lead to an increased maximum body size.
There are also giant tube worms in the ocean, and while they won't exhibit deep sea gigantism, they do still have a longer lifespan. The tube worms that live in hot hydrothermal vents, often only live 2 years...but the ones living at the cold ocean depths can have a lifespan of over 250!
Some animals that exhibit Deep Sea Gigantism...