We found these little guys whilst doing a beach clean. It seems that one man’s litter is another species handy substrate. Credit: Samantha Andrews/Ocean Oculus
Don’t let looks fool you. These critters may look a little dull but like all life on this planet, they are amazing. The first amazing thing? Their name.
These are pelagic gooseneck barnacles. That's right - gooseneck.
But what have they got to do with geese?
To get our answer, we need to go back in time to around the 13th century and look at another species - Branta leucopsis - the barnacle goose. These geese are a migratory species, many of them wintering across the UK, and breeding up in the Arctic during warmer summer months. Now back in the 13th century, the folks in the UK didn’t know about this migratory behaviour, so where they came from was a mystery…
Until someone spotted an (apparent) resemblance between the barnacles and the head of the geese. So what does this resemblance mean? Obviously (to 13th-century people) that the barnacles turned into the geese! And so the story was born, and the barnacles were given their scientific name - Lepas anatifera - meaning bearer of ducklings.
These barnacles can be found on pretty much in any ocean in the world. As long as there is something solid they can attach themselves to, these little molluscs are happy. They have been found living on piles and piers along coastlines but in middle of the ocean, anything will do – the hull of a boat (much to seafarers’ dismay), a buoy, some driftwood, and (as you can just make out in my photo below) the sole of a shoe. There has even been a report of these critters attaching themselves to sea turtles!
Want more? Here are a few other funky facts about these gooseneck barnacles.
My what a long… stalky thing you have!
You can probably tell from the photo that these animals aren’t exactly huge. Their shell (called the capitulum) is made up of plates and averages a total of 4 – 5 cm in length when fully grown. But that long black stalky looking thing that is attached to the underside of the shell you can see …well that can get up to a whopping 85 cm long! These "peduncles" are strong and flexible and act like a super-suction foot. Once the barnacle attaches itself to a surface, it can only be dislodged by a tremendous force. Its super-sucky strength comes from a ‘cement’ like substance that is generated in a special gland located inside the peduncle. This substance travels from the gland to the foot via some canals and hardens on contact with a substrate.
Getting down to business: How do the mate?
These critters are hermaphrodites – meaning they possess both male and female organs. When it comes to mating, these barnacles don’t hang around. Within 2 weeks of settling, they are sexually mature and considered fully grown within 6 weeks. As far as we can tell, they won’t self- fertilize but are quite happy to play with any of their neighbours that are within reach…. a lot. Although gregarious, these invertebrates are a bit fussy about when they spread their love. If it’s too hot (ideally not above 25 Celsius but no higher than 30 Celsius) or too cold (ideally not below 19 Celsius but certainly no lower than 15 Celsius) then they just aren’t interested. The ovaries apparently ‘disappear’ below 15 Celsius and above 25 Celsius. As for the penis, below 19 Celcius and above 25 Celcius, it becomes completely 'inactive'.