Gastropteron

Common Names

Gastropteron species are commonly referred to as "sea butterflies" or "pteropods," a name shared with other pelagic mollusks. The term "sea butterfly" often describes the overall appearance of these gastropods, emphasizing their graceful swimming movements and the distinctive wing-like lobes on their bodies.

Characteristics

Gastropteron species exhibit a variety of fascinating characteristics that distinguish them from other nudibranchs. These features include:

• Reduced Shell: Gastropteron, like many nudibranchs, lacks a prominent external shell, though they retain a small internal shell. This adaptation allows for greater flexibility and agility in swimming.
• Wing-Like Parapodia: The most striking feature of these sea slugs is the presence of large, flattened lobes or "wings" on their sides, known as parapodia. These structures provide lift and propulsion during swimming.
• Cerata: While most nudibranchs exhibit cerata (projections on the back), Gastropteron species do not. They are typically smooth-bodied with the parapodia dominating their body form.
• Predatory: Gastropteron are carnivorous, feeding mainly on small invertebrates, including other pelagic mollusks.
• Pelagic Lifestyle: These nudibranchs are pelagic, meaning they live in the open ocean, often in the water column, rather than attached to the seabed. They are strong swimmers, using their parapodia to navigate the water.

Environments

Gastropteron species are found in various marine environments, predominantly in tropical and subtropical waters. Their distribution includes:

• Open Ocean: They are most commonly encountered in the pelagic zone, drifting with currents or actively swimming.
• Coastal Waters: Some species may venture into coastal areas, especially during specific seasons or life stages.
• Deep-Sea Environments: Some Gastropteron species have been observed in deeper waters, although they are not as common in these habitats as in shallower, sunlit regions.

References

For further information on Gastropteron, refer to the following online resources:

• World Register of Marine Species (WoRMS)
• Sea Slug Forum
• iNaturalist