The barreleye is a small deep-sea fish, measuring about 6 inches (15 cm) long. Its most striking feature is its transparent head, which allows you to see the fish's internal structures ...

Its transparent head allows it to look upward ... Living in depths between 2,297 and 9,006 feet, this deep-sea fish is mostly known for being able to swallow up 10 times its size in food.

To move, this species uses two fins—one pectoral and one dorsal—that are so thin they are almost transparent. As with sea horses, sea dragon males are responsible for childbearing. But instead ...

Weedy sea dragons have very long, thin snouts; slender trunks covered in bony rings; and thin tails which, unlike their seahorse cousins, cannot be used for gripping. They have small, transparent ...