Glaucus Atlanticus Forster (1777):
Identification: The bright dark blue and silver body distinguishes this species. The cerata are elevated on three cushions per side of the body. The rhinophore and oral tentacle are short.
Size: 20-40mm
Location: Worldwide Tropical Oceans
Glaucus Marginatus (1860)
Identification: Similar to Glaucus Atlanticus, has multiple rows of cerata in each cluster
Size: 20mm
Location: Tropical and subtropical oceans
The main differences between these two species are:
- Glaucilla marginata has more cerata than Glaucus atlanticus, up to 137 in total
- the tail (metapodium) of Glaucus atlanticus is much longer than that of Glaucilla marginata
- Glaucus atlanticus is the larger of the two species – Glaucilla marginata only reaches 12mm in length
