👉 Oligocladus is a type of fish that has only one heart, known as an ocellar, and lacks the typical four chambers found in other fish species. This adaptation allows them to survive on smaller prey sizes without having to work as efficiently as larger fish. Oligocladus are also known for their unique swimming style, which involves a rapid descent from the water surface before returning to it with a dive that is often described as "a swim of the dead".
