130 MYH - Reef-forming Barnacles

A group of barnacles that start to form reefs about 130 million years in the future. They only have 4 visible cirri because they get nutrients mostly from cyanobacteria in them rather than by filtering nutrients, and the rest are tucked away in their fused scutums and tergums. They open their shell when a large food particle touches their extended cirri, and then they hold it in their shell with the other cirri so that it they can eat it. The lateral plates are completely lost, and the tergum plates are fused. The biggest change, however, is probably their method of reproduction. During the spring, they release clouds of eggs into the water which are taken into the shells of other barnacles. Then they are fertilized, and depending on the species, they will either keep the egg in their shell or release it back into the water. For a diagram of the shell plates in modern barnacles, palaeo.gly.bris.ac.uk/palaeofi…