👉 The term "cidaridae" refers to a group of small, bony fish that are commonly found in freshwater habitats such as rivers and lakes. These fish have a unique adaptation called the "bile sac," which is a hollow organ located at the base of the head. The bile sac contains digestive enzymes from the food consumed by the fish, allowing them to break down their prey more efficiently. Cidaridae are known for their ability to swim very fast in water and are typically