This squid’s mismatched eyes are actually the perfect pair.
The strawberry squid (Histioteuthis heteropsis) has one big eye and one small eye. Together, this improbable pair helps the squid hunt for food in the ocean’s twilight zone. The big left eye looks upward to spot shadows cast by prey in the dimly lit waters above. The eye’s tubular shape helps collect as much downwelling light as possible. Often, this eye has a yellow lens to see through the luminescent camouflage of its prey. The squid’s right eye is small and looks downward. This eye searches for flashes of bioluminescence produced by prey or predators lurking in the darker waters below. This squid is sometimes called the cockeyed squid for the remarkable difference in size between the two eyes.
Food is scarce in the deep sea, so animals must evolve unique strategies to find food. They must also find ways to avoid becoming food. Like many deep-sea animals, the strawberry squid is bright red. Red light does not reach the deep sea. There, a crimson coloration actually appears black and helps the squid hide from the gaze of predators like sperm whales, dolphins, tunas, swordfish, and sharks. Small light organs called photophores also dot the squid’s body to help mask its silhouette from predators prowling the waters below.
Maximum size: mantle length to 13 centimeters (5 inches)
Depth: 200–1,000 meters (660–3,300 feet) during the day, migrating to shallower waters at night
Habitat: midwater, twilight (mesopelagic) zone
Range: eastern Pacific Ocean
Diet: shrimp, fishes, and other squids
Bush, S.L. and B.H. Robison (2007). Ink utilization by mesopelagic squid. Marine Biology, 152: 485-494. doi.org/10.1007/s00227-007-0684-2
Thomas, K.N., B.H. Robison, and S. Johnsen (2017). Two eyes for two purposes: In situ evidence for asymmetric vision in the cockeyed squids Histioteuthis heteropsis and Stigmatoteuthis dofleini. Philosophical Transactions of the Royal Society B, 372: 20160069. dx.doi.org/10.1098/rstb.2016.0069