What are some translucent rocks

The barnacle
and the rock barnacles


Tide today, click below:

A colony of 11 young barnacles with floats of the species Dosima fascicularis.
which are attached to a yellow floating beam that they themselves secreted.
You are never as well served as by yourself!

  The barnacles and rock barnacles are strange animals sometimes found in Brittany, the first among marine debris, i. H. the deposits of seaweed and various marine litter left on the beaches by the waves, and the second more in fish shops.

Despite the presence of a clam shell, both are crustaceans that live in colonies that can contain thousands of individuals. The barnacle lives off the coast, suspended from a floating object: buoy, boat hull, plastic canister, tree trunk, wrecked algae or a simple piece of wood. That is why it is sometimes deposited on the strike by the waves. Just one way Dosima fascicularis (Photo above) produced their own floating support. The barnacle is a pelagic nomad who is carried by the currents.
The rock barnacle lives forever Studies of this small marine fauna are still in their infancy. They are often very promising in unsuspicious areas. The extraordinary adhesion of the cirrus to its backing could lead the research of the adhesive manufacturers to particularly resistant organic adhesives. Other marine animals, such as sea cucumbers, produce an instant cement remover to help them move, which may be of interest to ship antifouling manufacturers. Paradoxically, we find that humans are responsible for the rapid disappearance of a large number of marine species that have not yet been studied. Look for the fault ... on a rock chipped by the waves. Its support can be a reef at sea, a rock that sometimes emerges, or the foot of a cliff. The animal is therefore sedentary and therefore it can be fished at low tide because it is edible. But be careful, the fishery is regulated.

The barnacle (Lepas or Anatifa- anatifera)

This strange crustacean, of which there are a number of different species, is made up of two parts:

- a head protected by white limestone plates welded together (maximum 5). It's the capitulum.
- a fleshy stem up to 90 cm, attached to the support floating on it.

Group of barnacles resting on the hull of a sea kayak
of the Polish navigator.This great athlete died of exhaustion in February 2021 at the age of 74 while reaching the summit of Kilimanjaro. Alexander Doba on his arrival in Le Conquet on September 3rd, 2017 after his 3rd crossing of the Atlantic in a rowboat1
© Photo YL

In the water, the capitulum opens to release a pair of black silks called cirri, which spread and constantly scour the area to capture suspended plankton. This is how the animal feeds. The Cirri are retractable. The water entering the capitulum also bathes its gills, which allows it to be oxygenated.

The barnacles are difficult to eat and are neither fished nor marketed.

A sea snake in Le Conquet!

This colony of barnacles was attached to a palm trunk,
which the sea deposited on the beach of Portez, at the foot of the headquarters of the Iroise Marine Natural Park

Thousands of small crustaceans that likely crossed the Atlantic
hang on this wreck

They all belong to the species Lepas anatifera.
A cub is glued to an adult's stem

When places are expensive, they stare straight at each other
© Photos: YL February 7, 2020

The rock barnacle ( Pollicipes pollicipes)

Group of rock barnacles attached to a rock.
© Photo Sébastien Brégeon / Agence des aires marines protégées

© Photo Frédéric André / DORIS

In French it is sometimes spelled "pousse-pied", but this word is also used to denote a type of sledge that will slide on the mud. It is therefore preferable to write it as pouce-pied, an immutable name derived from the animal's distant resemblance to the tip of a toe.
The scientific name comes from Latin pollex, Thumb and pes, Foot.
Like the barnacle, it consists of a stem and a capitulum. But its stem, short, thick, and fleshy, is almost black with an often reddish base.
Its capitulum is equipped with 5 whitish oval plates, to which at least 8 more much smaller plates are added, separated by a black integument.
The capitulum is bordered with red.
With a very iodized taste, the meat on the stick is easy to eat, especially appreciated in Portugal and Spain. But the rock barnacles have been fished so much that it is feared that they will disappear. Fishing in the Iroise Sea is only allowed during two seasons: from January 16 to March 14 and from September 16 to November 14. Catches are limited to 3 kg per person per day.

An elaborate classification

Because of their white shells, barnacles have long been confused with clams. In the Middle Ages, it was even believed that these animals, whose plates were shaped like a beak, were wild duck eggs or a species of goose called the brent goose! In addition, the French name Anatife comes from Latin anas, anatis : Duck. Anatife, abbreviation for anatifère = who produces ducks. The English called it "barnacle" (geese) and the Germans "barnacle". These quirky names have become part of everyday language.
The rock barnacles, with the more complex capitulum, did not experience this confusion.
All these mussels, whose shell is made of limestone, are different from shrimp, crabs, lobsters, etc ..... whose shell is made of chitin. The presence of their cirri counts them among the "cirripeds" (barnacles) that collect other marine species such as barnacles, which are often found on coastal rocks. It was not until the 19th century that studies by biologists on barnacle larvae revealed that they belonged to the crustacean arthropods.
Nevertheless, they fascinate the hiker with their unusual appearance. Another reason to respect them.

Rock barnacles colony
at the foot of a cliff
© Photo Laurie Commenge / Agence des aires marines protégées

Predictable proliferation

Completely dependent on all kinds of floating objects to cling to, the barnacles have a bright future. In fact, we don't stop dumping a significant amount of litter into the sea. The smallest, less than 5mm, congregate in the middle of the oceans to form what some already call gyras, or plastic continents. Their size is too small for barnacle larvae to cling to. But larger floating objects are supports to hold them in place. It is therefore already foreseeable that the various types of barnacles will experience a considerable expansion.
What are the consequences? What we know today is that, like fish, their bodies already contain a lot of microplastics. And that these are absorbed by their predators, seagulls or sea turtles and by all scavengers. Inevitably, from predators to predators, these microplastics will accumulate in organisms and end up in that of the super-predator who is humans.

-1- The photo shows different types:
  - Lepas anatifera : These are individuals whose capitulum consists of white spots with an orange-yellow border. Their black stalk can reach 7 to 8 cm, shorter and more translucent in young creatures. The cirrus is almost black. This type is common.
  - Lepas pectinata : The capitulum is smaller. the cirrus is clear.
 - Conchoderma auritum : Their calcareous shells are tiny, housed in a capitulum that appears to be just a bulge on the stem. This species of open sea animal often clings to whales.

Many thanks to the team of the Iroise Marine Nature Park and Frédéric André from the DORIS association, who kindly provided the necessary documents, carried out the identifications and checked this text.



See the following page from ZOOM-NATURE on the Internet:
Anatifes: experts en dérive

Riou Y. and Giraudon D., 2013, ed. Yoran Embanner, 272p.

Hayward P. et Nelson-Smith T., 2014, ed.Delachaux & Niestlé, 351p.

Loyer B., 1995, Collection Nathan Nature, ed. Nathan, 160p.

A website :
The indispensable address for all quality documentation on the flora and fauna of the oceans and freshwater: