The Disposable Penises of a Nudibranch.
Little did I know, when I shot this critter, that it had a kinky talent of regeneration.
I say ‘it’, because nudibranchs are simultaneous hermaphrodites. During mating, the pair will impregnate each other. With the penis location on the right side, when the nudibranchs line up, they can inseminate themselves at the same time. The act takes anywhere from a few seconds, to a few minutes.
Post-coital observations (for Science) showed that as the nudibranches pushed away from each other, they ‘shed’ their penises.
In less than 24 hours, however, the nudibranchs had regenerated their penises and were able to mate again.
Apparently the reason for this being that a large amount of the penis is stored coiled up in a spiral inside their bodies, used to replace the missing part.
So what’s the advantage?
The researchers say that in the first act of copulation the penis may be used to remove any sperm left by any competitors that its partner has mated with.
With the first penis and the rival sperm then abandoned, the second penis can be used to inject the sea slug with another dose of its own sperm, ensuring that their genes are the ones that are passed on.
Photo: Samantha Craven
Journal Article: http://rsbl.royalsocietypublishing.org/content/9/2/20121150
Anatomy of a starfish
Brownbanded Bamboo shark (Chiloscyllium punctatum) profile by Samantha Craven
Bamboo sharks are always a delight to encounter. Their little “moustache”, seen here in profile, is a pair of barbels, effectively taste buds on a stick, used for finding prey.
Classified as ‘Near Threatened’ by the IUCN Red List, these sharks face the myriad of threats to all sharks, in addition to pressure from the aquarium trade.
How I study for finals (:
so we dissected squid in biology last week… letter “m” was no where to be found…
Bob and Sid: The bicephalic squid?
Well not quite. In 2003 in Woods Hole, Massachusetts, scientists discovered what appeared to be a two headed squid. Upon dissection, they turned out to be a small squid (Sid) stuck inside a large one (Bob).
Bob’s organs were atrophied and shrivelled, meaning that Sid had been living there for a while prior to capture.
The photos have recently been ressurected by The Octopus News Magazine Online.
Nematocysts: The Stinging Cells of a Coral
The diagram above shows the anatomy of a nematocyst cell and its “firing” sequence, from left to right.
On the far left is a nematocyst inside its cellular capsule. The cell’s thread is coiled under pressure and wrapped around a stinging barb. When potential prey makes contact with the tentacles of a polyp, the nematocyst cell is stimulated. This causes a flap of tissue covering the nematocyst—the operculum—to fly open. The middle image shows the open operculum, the rapidly uncoiling thread and the emerging barb. On the far right is the fully extended cell.
The barbs at the end of the nematocyst are designed to stick into the polyp’s victim and inject a poisonous liquid. When subdued, the polyp’s tentacles move the prey toward its mouth and the nematocysts recoil back into their capsules.
(read more: NOAA)
promise-and-precision: Hawaiian Bobtail Squid scientific illustration. Re-editing later on this weekend, so I’ll post again when I do. - colored pencil.