Here are the most interesting transparent animals, from icefish to jellyfish to frogs to butterflies! Nature sure is very interesting!
1. Transparent Frog
Native to Venezuela, the Glass Frogs belong to the amphibian family Centrolenidae (order Anura). While the general background coloration of most glass frogs is primarily lime green, the abdominal skin of some members of this family is transparent, so that the heart, liver, and digestive tract are visible through their translucent skin. (Photo by Heidi and Hans-Jurgen Koch)2. Transparent Head Fish
This bizarre deep-water fish called the Barreleye (Macropinna microstoma) has a transparent head and tubular eyes. It has extremely light-sensitive eyes that can rotate within his transparent, fluid-filled shield on its head, while the fish's tubular eyes, well inside the head, are capped by bright green lenses. The eyes point upward (as shown here) when the fish is looking for food overhead. They point forward when the fish is feeding. The two spots above the fish's mouth are not eyes: those are olfactory organs called nares, which are analogous to human nostrils. (Photo by MBARI)3. Transparent Butterfly
Found in Central America, from Mexico to Panama, the Glasswing Butterfly (Greta Oto) is a brush-footed butterfly where its wings are transparent. The tissue between the veins of its wings looks like glass. (Photo by Hemmy)4. Transparent Squid
Found on the southern hemisphere's oceans, the Glass Squid (Teuthowenia pellucida) has light organs on its eyes and possesses the ability to roll into a ball, like an aquatic hedgehog. It is prey of many deep-sea fish (eg goblin sharks) as well as whales and oceanic seabirds. (Photo by Peter Batson)5. Transparent Zebrafish created by scientists
This see-through zebrafish was created in 2008 by scientists so they can study disease processes, including the spread of cancer. The transparent fish are allowing researchers at Children's Hospital Boston to directly view fish's internal organs and observe processes such as tumor growth in real-time in living organisms. (Photo by LS)6. Transparent Icefish
Found in the cold waters around Antarctica and southern South America, the crocodile icefish (Channichthyidae) feed on krill, copepods, and other fish. Their blood is transparent because they have no hemoglobin and/or only defunct erythrocytes. Their metabolism relies only on the oxygen dissolved in the liquid blood, which is believed to be absorbed directly through the skin from the water. This works because water can dissolve the most oxygen when it is coldest. In five species, the gene for myoglobin in the muscles has also vanished, leaving them with white instead of pink hearts. (Photo by uwe kils)7. Transparent Amphipod
Called Phronima, this unusual animal is one of the many strange species recently found on an expedition to a deep-sea mountain range in the North Atlantic. In an ironic strategy for survival, this tiny shrimplike creature shows everything it has, inside and out, in an attempt to disappear. Many other small deep-sea creatures are transparent as well, or nearly so, to better camouflage themselves in their murky surroundings, scientists say. (Photo by David Shale)8. Transparent Larval Shrimp
Found in the in the waters around Hawaii, this transparent larval shrimp piggybacks on an equally see-through jellyfish. (Photo by Chris Newbert/Minden Pictures)9. Transparent Salp
This jellyfish-like animals known as Salps feed on small plants in the water called phytoplankton (marine algae). They are transparent, barrel-shaped animals that can range from one to 10cm in length. (Photo by DM)10. Transparent Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. They are found in every ocean, from the surface to the deep sea. Many jellies are so transparent that they are almost impossible to see. The one above is from the Arctapodema genus, with a size of an inch-long (2.5-centimeter-long). (Photo by Bill Curtsinger) 
