Barnacles are sticky little crustaceans creatures. They look like mollusks with their hard shell-like covering, but actually, barnacles are related to lobsters and crabs. They are members of phylum Arthropoda as they possess jointed appendages, a segmented body, an exoskeleton, and bi-lateral symmetry. 

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With a tiny brain and no true heart, the common barnacle dwells in shallow marine environments on almost any sturdy surface that gets covered by water. They feed on plankton or Algae that they sweep from water through their feet. 

What Barnacles Look Like?

Barnacles are one of the oldest marine surviving creatures on earth. They have a volcano shape body with the secretion of 4 to 8 calcite plates to protect their bodies. Their size varies from 8.5inch to 1inch in length and 0.5 to 1.5inches in height, depending upon their species. Their color ranges from yellow, white, or black. Their actual weight is still unknown, but approximately a single individual weighs around 75 to 800mg.

They have firm bodies with one eye, one head, and a telson but no abdomen or thorax. They have only a few internal organs with no heart or gills. They have a sinus close to the esophagus that performs a similar function as the heart. Barnacles breathe and eat through their feet called cirri. 

Barnacles are sessile animals. They have an opening on top of their body, called the operculum, which has a door. When barnacles sweep tiny food particles (microscopic organisms) from water by their feet, they pass the food to their mouths through that door. They remain attached to the rocks and each other through one of the most powerful natural glue. Once the barnacles get settled, they become sessile and may not move for the rest of their lives.