Blisterin’ Barnacles! The Secret Life of Barnacles
“What was the coolest thing you saw at the beach today?”
The answer to that question is rarely, if not ever, “The barnacles!!”
You might think there’s nothing to these seemingly boring white rock decorations, but believe me, they are having an absolute party underneath those white calcareous plates.
What even are they?
Barnacles are related to crabs! They are in the same subgroup (subphylum), Crustacea, under the group (phylum) Arthropoda. A distinctive overlying trait of arthropods is segmentation of the body and jointed appendages, such as legs. This trait is very apparent in most organisms in this group like insects, shrimps, spiders, crabs, and lobsters.
So how the heck do these things, belong in the group Arthropoda? Where are its jointed appendages?
To get to the bottom of this mystery, we will have to rewind time a bit to when this barnacle was just a wee zooplankton (baby).
Baby Barnacles!
Barnacles like most marine invertebrates start off as tiny little zooplankton.
Below, is an an early larval stage of an acorn barnacle moments after hatching, this stage is called the naupliar stage.
WOAH! LOOK AT ALL THOSE JOINTED LEGS AND SEGMENTED BODY SECTIONS!!
As you can see by this nauplius larvae trying its best to swim in a microscope slide, this stage is what allows barnacles to disperse, and get to where we eventually see them on rocks and docks.
Here is a more complete look at the life cycle of barnacles to get a better picture of how they go from babies to adult barnacles. (If you are interested in a more in depth exploration of the life cycle, check out this video!)

What happened to all those segmented legs in the naupliar stage?
If you spend a little quality time with adult barnacles under water, you may start to see them feed!
The fan-like appendages coming out to feed are actually their legs and they are called cirri!
You may be wondering things like, “What are they eating?” and “I don’t really see the cirri catching anything??”
That’s because they catch tiny plankton in the water by filtering and combing the water. We can’t really see what they’re catching because most of the plankton they’re feeding on are microscopic.
Here is a picture of their moult to get a better look at their structure! Take a look at the hairs coming off the cirri. They are there to maximize the capturing of plankton. MMMMM yummy.
(Barnacles also have another incredibly long thin appendage used for something very different. If you’re interested in barnacle copulation, check out this video!)
Thanks, barnacles!
Barnacles provide services that support the maintenance and creations of other ecosystems. Just by existing, adult barnacles create habitats for other organisms that need a place to settle. They also help purify the water as they feed on suspended dead materials in the water in addition to plankton through their filter feeding!
Barnacles are important to our ecosystems, so we want them to stick around. Climate change however, could pose a potential threat to barnacle populations. To better understand how climate change would affect barnacles, we exposed adult barnacles to higher temperature water to see how it would affect their feeding rate. (Here’s a picture of us observing their feeding rate)

Hopefully by better understanding the how climate change would affect barnacles, we will be better equipped to deal with the effects and make sure that our barnacle friends are doing well 😀