Range: All oceans except the Arctic

Habitat: From the sunlight zone (epipelagic) to the midnight zone (bathypelagic)

Size: 4 inch (10cm) to over 6.5 foot (2m) mantle length

Diet: Small fish and crustaceans

Threats: Whales and seabirds

Lifespan: Unknown (Likely short like other squids)

Transcript:

Today on Animal Fact Files we’re discussing glass squids. These squids get their common name because they are transparent, like a pane of glass, especially when they're young. There are approximately 60 living species of glass squid and they have another common name: the cranch squid. Longtime viewers of this show may remember that name from a previous episode on the colossal squid; these animals are one in the same! Colossal squid are classified in the glass squid family. Glass squids are distinct from other squids because of the connections of their heads to the mantle and funnel - it has nothing to do with their transparent nature!

Most glass squids have thin fins and a bulbous body. This is filled with ammonium chloride which is less dense than sea water. This means that a glass squid is neutrally buoyant and doesn't sink or rise in the water column unless it wants to! These squids range in size from a mantle length of about four inches (10cm) to over six and a half feet (2m) long! They have eight arms and two tentacles with clus at the end. In some species, like the colossal squid, these clubs come equipped with hooks to defend themselves from predators.

Glass squids have other anti-predator adaptations, as well. These invertebrates are bioluminescent meaning they produce light. Specifically, they have light producing organs right under their eyes. While the squid's translucent body almost makes it invisible in the ocean, its eyes and internal organs can still cast a shadow to predators lurking below. So, glass squids have vertically aligned organs which produce almost no shadow from light hitting them from above. Their eyes, which would cast a shadow, are lit from underneath, like shining lower lash line eyeliner. This light is the same color as the light from above, so, in essence, they disappear when seen from the sides and below! Predators to glass squids include whales like sperm whales as well as seafaring birds like an albatross. In turn, glass squids eat fish and crustaceans.

Female glass squids also produce light at the tips of their arms to attract a mate. Their eggs are fertilized internally and released sometimes in large batches all at once or in small batches over time. Young glass squids live closer to the surface of the ocean than the adults. The juveniles look different from adults, but they change as they develop. Their stalked eyes and fins change position and shape, they develop more pigment, and they gain more light producing organs. Some may even lose their tentacles! In fact, glass squid juveniles look so different from the adults they've previously been classified as different species! As they get bigger, glass squids move down the water column into deeper parts of the ocean. These cephalopods have been documented more than a mile (1.6km) below the waves.

Glass squids have another anti-predator defense: they produce ink! They also get another common name from one of their resting positions. They'll hold their arms and tentacles over their head giving them the appearance of a cockatoo; so glass squids are also known as cockatoo squids! It's unknown how long glass squids live, but there's evidence to suggest they're like other cephalopods who die shortly after mating, so their lifespan is likely rather short.

For more facts on glass squids, check out the links below. Give a thumbs up if you learned something new today. Thank you to our Patrons SpikeSpiegel93, Dad, and everyone else for their support of this channel! And thank you for watching Animal Fact Files!