Pteropoda

Common Names

Pteropods are commonly called "sea butterflies" or "sea angels" due to their distinctive wing-like structures used for swimming. Thecosomata are often referred to as "sea butterflies" because of their shell, while Gymnosomata, lacking a shell, are often called "sea angels."

Characteristics

Pteropods are characterized by their unique adaptations for swimming:

• Parapodia: These are wing-like appendages that allow pteropods to swim through the water by flapping them like wings. They have a hydrostatic skeleton which helps them maintain their shape and propel themselves through the water.
• Shell (Thecosomata): Thecosomata species have a thin, transparent shell that provides protection and buoyancy. It is typically coiled and can be shaped like a cone, a spiral, or a disc.
• Absence of Shell (Gymnosomata): Gymnosomata species lack a shell, but they have evolved other adaptations to compensate, such as a more streamlined body shape and stronger swimming muscles.

Environment

Pteropods are found in all the world's oceans, but they are most abundant in the surface waters of the open ocean, where they feed on plankton and other small organisms. Some species, such as the "sea angel" (Clione limacina), are adapted to colder waters, while others are found in warmer regions.

Importance

Pteropods play a vital role in the marine ecosystem. They are an important food source for a variety of marine animals, including fish, whales, and seabirds. They also contribute to the ocean's carbon cycle by incorporating calcium carbonate into their shells, which can sink to the ocean floor when they die.

References

For more information on pteropods, refer to these reliable sources:

• Wikipedia
• World Register of Marine Species
• Smithsonian Ocean Portal