page_title: Teuthowenia megalops
section_title: Ecology and biology
hierarchical_section_title: Teuthowenia megalops / Ecology and biology
caption_attribution_description: Teuthowenia megalops model(?) at the Smithsonian National Museum of Natural History
context_page_description: Teuthowenia megalops, sometimes known as the Atlantic cranch squid, is a species of glass squid from the subarctic and temperate waters of the northern Atlantic Ocean. They are moderately sized squid with a maximum mantle length of 40 cm. Their very large eyes are the source for the specific name megalops. Like other members of the genus Teuthowenia, they are easily recognizable by the presence of three bioluminescent organs on their eyeballs.
context_section_description: Like other members of the family Cranchiidae, Teuthowenia megalops possess a remarkable flotation system that enables them to remain in the water column at neutral buoyancy. The system uses enormous bilobed coelomic chambers filled with ammonium chloride derived as waste products from their nitrogen metabolism. The ammonium chloride has a lower density than water, which enables the squid to float. In experiments, puncturing the chambers and draining the ammonium chloride resulted in the squid sinking rapidly. The chamber is also lined with muscles that contract and expand regularly in peristaltic waves. The movement draws water into the mantle cavity and pushes it out again through the funnel, aerating the gills in the process.
  As a result of this adaptation, Teuthowenia megalops are sluggish swimmers. Unlike other squids, they do not need to contract their mantle muscles to breathe, but their modified flotation and respiratory systems restrict their ability to jet away from threats. They generally float passively in the "cockatoo" posture typical of glass squids (which are also known as cockatoo squids for this reason). They resemble a horizontal cockatoo, hence the name. In this posture, they rotate around their spindle-shaped digestive glands, the only internal organs of the squid clearly visible through their mostly transparent bodies. Regardless of the direction their heads or mantles are facing, the digestive glands are always kept oriented vertically.
caption: Teuthowenia megalops from the Smithsonian National Museum of Natural History shown in the "cockatoo" posture. The spindle-shaped digestive glands remain oriented vertically, no matter what direction the squid's head and body are facing.
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