Most people who have been at the coast have seen barnacles but very few people know much about them.
Well, let’s start off simple. Barnacles are crustaceans and are related to shrimp and crabs. Yeah, that’s right. Kind of hard to tell at a glance. They are very common and latch onto anything stationary and that is because they are sessile, which means they lack the ability to move themselves. Those shells they live in are actually attached with a cement gland that the barnacles have. Yes, literal, natural cement.
You know those little feelers that they stick out to eat? Well those are actually its legs that it uses to filter feed. These are called cirri and can actually help with its ‘breathing’. As they are filter feeders they generally tend to have a diet consisting of plankton and other microscopic organic materials.
When someone says barnacle, people usually think of the small rock-like acne on rocks and ships and while those are barnacles and certainly the most common, known as acorn barnacles.
However there are literally around a thousand species of barnacles. Such as the goose barnacle which have a long stalk.
These are actually edible and widely consumed, considered a delicacy in places such as Portugal and Spain known as percebes
It is also eaten in other places, like Morocco and historically consumed by the indigenous people of California.
While we are on goose barnacles, there was a historic misconception regarding these crustaceans and geese. This was when people did not know that birds migrated and thus had never seen them nest in Europe. It was actually believed that goose barnacles were the eggs or young of geese and that full grown geese would emerge from them. This is generally a medieval era idea and is attributed to the christian church.
Most barnacles, with few exceptions (the goose barnacle is actually an exception), are hermaphroditic, meaning they do if fact contain both sexual organs. Now if you will recall, barnacles are sessile and cannot move. As such, this does make sexual reproduction difficult. To combat this, barnacles have evolved in the most hilarious way.
Barnacles have extraordinarily long penises.
Barnacles actually have the largest penis to body size ratio in the entirety of the animal kingdom.
No I’m not joking.
Behold.
Anyways we’ve discussed that barnacles can only like to situate themselves on stationary or slow moving objects, like rocks or turtles. Well did you know there is a species that actually has chosen to live upon dolphins?
Yep! There is a genus that lives exclusively on the fins of porpoises!
In order to get a good grip though, they ‘bite’ into the skin and dig in to hold on leaving a star shaped scar when they die and fall off.
This next section is going to cover parasitism so just to make sure everyone is comfortable the paragraphs and pictures will be censored. Please look at your own discretion.
Did you know that barnacles can be parasites? Neither did I until yesterday. It’s true and there are quite a few that have taken to this life style. Rhizocephala is a parasitic barnacle that goes after its cousins, mainly crabs and lobsters. When a larva finds a female crab, it will pierce the crab’s egg sac with a needle-like appendage inject a clump of cells. Now that this has happened, the crabs fate is sealed. It will grow inside the crabs body, wrapping around its organs, muscles, and even eyes. It will continue growing to the point it will bulge out of the egg sac, changing the crab eggs to its own eggs. Another barnacle will come along, fertilize the eggs, and then the crab will climb atop a rock and release the larva, letting the process happen again. This barnacles anatomy has deviated to this very specific lifestyle that it in comparison to other barnacles it is almost unrecognizable.
But perhaps that wasn’t interesting enough for you. Well that’s fine because I have another one. This one has chosen its host to be that of the dogfish, a species of small, deep sea sharks. Most barnacles that hitch a ride generally do not harm the host but this one is an exception. This barnacle does not have a shell and thus will dig itself into the dogfish and take refuge under the skin, in the eyes, the spiracles, and mouth. Sometimes even in the sexual organs, effectively castrating the shark. It has roots that will anchor surprisingly deep into the dogfish and sap the nutrients from the surrounding tissue.
Anelasma squalicola anatomy vs a goose barnacle
September 2, 2022
Sources lost