|Image: Bernard Picton, National Museums Northern Ireland|
Oaten Pipe Hydroids are hydroids! This means they're in the phylum Cnidaria, alongside jellyfish, corals, sea anemones and others who challenge our understanding of what it means to be an animal.
Oaten Pipes are rather large as hydroids go, standing 10 to 15 cm (4 to 6 in) tall on a long, unbranched stem. That's where they get their name from, since oaten pipes are musical instruments made out of bits of oat straw chewed a little on one end and with holes bored along one side. They probably went out of fashion when people got money.
|Image: Eric Burgers|
Pretty sure those bead things are gonotheca, where sperm is produced or eggs are incubated.
Oaten Pipe Hydroids are not hermaphrodite!
Oaten Pipe Hydroids are found on rocks and boulders of the North Atlantic, from shallow coasts to depths of over 200 metres (650 feet). They do particularly well in areas swept by currents. They are in fact a lot like the kind of shepherds who play the oaten pipe, waking up to the desolate hills, their very faces calloused by the crashing winds.
|Image: marlin harms|
The Bushy-backed Nudibranch (Dendronotus frondosus), the hydroid's nemesis
Unlike a lot of hydroids, the Oaten Pipe doesn't produce medusae.
Medusae are what we call "jellyfish". In many hydroids, they detach from the rest of the body and swim off before they reproduce. It's a good way of finding new, unconquered territory to settle in. But Oaten Pipes don't do this, they prefer to do all their reproduction right where they stand. Sometimes that means whole colonies of Oaten Pipe Hydroids develop...
|Image: SERPENT Project|