3. Deep-sea gigantism
Ever heard the phrase Deep-sea gigantism? It means precisely what the name suggests. The tendency for deep-sea animals to display a larger size than their smaller, more familiar relatives.
For example, look at giant and colossal squids. The colossal squid is the larger of the two and can grow up to 46 feet or 14 meters long. The average length of a school bus. Another example is the Japanese spider crab with a maximum leg span of almost 13 feet or 4 meters. There’s also the giant oarfish, which can grow to over 56 feet or 17 meters long. And the giant isopod, which looks enormous compared to its smaller relatives. We don’t know exactly what causes the creatures increased size. It could result from adaptation for scarcer food, greater pressure at depth, extreme temperatures, complete lack of sunlight or other unknown reasons.