"Opisthobranchia" is a term that is used informally to capture this large and diverse group of gastropods. Opisthobranchs are otherwise known as the 'butterflies of the sea', which includes the beautiful nudibranchs. For the purpose of being able to group together all these similar types of species together all nudibranchs, pleurobranchs, sea hares, bubble snails and umbrella slugs that we see in Sydney have been grouped together as sea slugs.
In this website Sea Slugs have been grouped together into collections under the following orders:
In this website Sea Slugs have been grouped together into collections under the following orders:
- Subterclass Ringipleura
- Order Nudibranchia (Nudibranchs)
- Order Pleurobranchida (Sidegill Slugs)
- Order Nudibranchia (Nudibranchs)
- Subterclass Tectipleura
- Order Aplysiida (Sea Hares)
- Order Cephalaspedea (Headshield Slugs / Bubble Snails)
- Order Umbraculida (Umbrella Slugs)
- Order Aplysiida (Sea Hares)
Opisthobranchs have both male and female organs. When nudibranchs reproduce they line each other up head to tail, both matching their female sexual organ with the other’s male sexual organ and then copulate which can last up to days depending on the species. Once fertilised they each will lay thousands to millions of eggs. Sea hares, however, mate by mounting another from behind in large mounting chains where the one at the back loses out.
|
Nudibranchs have no hard shells to protect themselves and so instead use colour as their main mechanism of defence. By appearing toxic many predators leave them alone. Their main predators include starfish, anemones, crabs, flatworms and more commonly, other opisthobranchs.
|
|
|
Anatomy: