The gang discusses two papers about encrusting organisms. The first paper looks at evolutionary patterns of bryozoans to infer environmental triggers for shifts in the ways bryozoans calcify. The second paper uses the distribution of encrusting organisms on spirifd brachiopods to infer the ecology of both the encrusters and the brachiopod they grew on top of. Meanwhile, James discovers new foods, Amanda constructs a worm, and Curt gets confused and makes it everyone's problem.

Up-Goer Five (Curt Edition):

The friends talk about two papers that look at animals that do not move around much and live stuck to other animals. The first paper looks at a group of animals that grow together with their friends and grow really well on top of other things. This group makes hard parts out of stuff it gets from the water it lives in. When there are changes in ways big rocks move, this changes the types and number of things in the water that can be used to make hard parts, which can make one way of making hard parts easier than others. Most of these animals today make hard parts in the way that is not the way that is easy with how the water is today, but there are some groups that do use the easy way. This paper looks at how these groups changed over time using a family tree for the group, and they find that these groups that make their hard parts the easy way today may have started doing this when the water changed to the way it is today.

The second paper looks at a group of animals with hard parts on the top and bottom that lives on the bottom of the water place and eats food by moving water into it to pull the food from the water. These animals do not move around much and they have big hard parts, so they are places where these animals that grow on top of other animals like to grow on top of. This paper looks at how these animals grew on top of these other animals to see if there are anythings that are the same or different between groups of animals that are growing over these animals. This is also used to see if we can learn things about how the animals with hard parts on the top and bottom which are having things grown on top of them are living, because some ways things grow over these animal could only happen if the animal with hard parts on the bottom and top are already dead. This paper shows that a lot of the ideas we had about how this animal with hard parts on the top and bottom lived are wrong. These animals did not change the way they sat at the bottom as they got bigger, and we know this because the parts of the animal that would be in the ground are not covered with animals that would grow on top. The only times we see these parts covered are when the animals that grow over would grow over the parts where the animal with hard parts on the bottom and the top would use to get water into to eat, which means that animal must already be dead.

References:

Saulsbury, James G., et al. "Evolution of skeletal mineralogy in cheilostome bryozoans from calcite to aragonite seas." Geology 53.11 (2025): 914-918.

Vantoorenburg, Haley N., et al. "Palaeoecology of Middle Devonian epizoans and their Paraspirifer hosts." Palaeontology 69.2 (2026): e70050.