Gooseneck barnacles were originally believed to be birds that spontaneously generated the
barnacle goose (Branta leucopsis) to which they look similar. Later,
it was obvious those suggestions were laughable, the animals were clearly
molluscs and related to snails according to Linnaeus, the father of modern taxonomy. It
wasn’t until the early 1800s that a British army surgeon was like, “well what do you know,
these things have crab babies” - or something like that - in reference to the swimming larval stages
of immature barnacles. Today it’s known that barnacles are crustaceans, like a crab or lobster.
One of the five calcareous plates that make up an acorn barnacle’s outer shell
is called the ‘carina’ which is the same name given to the keel of a bird.
‘Carina’ also means “a keel-shaped structure”, but we think it’s worth
mentioning because it means that barnacles have more than one connection to birds!
There’s an entire subclass of barnacles (Facetotecta) in which adults have never
been observed or recorded in the wild;
they’re known only from their larval stage. Scientists have raised them in laboratory
settings and believe the adults are likely parasites, but this hasn’t been confirmed.
The adhesive barnacles produce to secure themselves to surfaces is
called "cement" but it's nothing like the cement made by humans,
nor it is similar to the "cement" made by other sessile animals like mussels and tube worms.
Barnacle cement is one of the strongest known natural adhesives. To date,
there isn't a human-made cement available that works as efficiently as the barnacle's cement.
Barnacles are called "fouling organisms" because they attach to floating objects in
the ocean. For both human-made objects, like boats, as well as larger animals,
like sea turtles, this causes drag. Their fouling behavior costs millions of dollars
a year ranging from removal expenses to fuel efficiency drops in seafaring vessels.
Barnacles can attach to almost any surface, but they're no match for porous silicone.
Silicone is synthesized and found in implants, contact lenses, shampoo, and more while silicon
is naturally occurring and makes up minerals, like quartz which is a component of sand. In
natural settings, porous silicone surfaces inhibited permanent barnacle attachment.
This could be big news for all those people spending millions of dollars to remove barnacles.
People eat barnacles. In fact, some barnacle species sell for
$37/pound ($17/kg) or more depending on their availability. If you think about it,
they probably taste something like crabs or lobsters since that's who they're related to!
There are over 400 named fossil barnacles and, like modern barnacles, they can be
used to estimate migration routes of the oceanic animals they attach to.
Barnacle shells help give clues to the temperature and chemical composition of
the water in which they form. Since barnacle shells are continuously forming, if they move,
such as when they’re attached to a whale, they can provide a breadcrumb trail of where they’ve been.
Though acorn and gooseneck barnacles have shells for defense, they're eaten by snails,
like whelks, who can bore through them and then turn them into soup inside their
own home. It’s kind of like a spider using its venom to liquify the prey in its web.
The final larval stage of the acorn barnacle is
called the 'cyprid' and its main goal is to find a place to settle down for life.
Barnacle larvae are able to attach and then release from a surface that isn't favorable to
them. Once they attach as adults, however, they're stuck there. Even after barnacles die, they're
still stuck to wherever they settled - at least for the adults who settle in the first place.
You’ve also probably heard that barnacles aren’t mollusks, they settle head-first,
and many have a giant penis, but if you weren’t aware of these facts, you can learn all about
them and more in our full barnacle episode. There’s a card on screen you can click right now.
Go ahead. Click it! There’s lots to learn! And thanks for watching Animal Fact Files!