the anterior and posterior end of the egg case serve to better secure the egg case in between rocks, as well as protection against potential predators. Threats Predation on egg cases is thought to be a major source of mortality for developing oviparous sharks, skates and chimaeras. In general, predation is the leading cause of mortality for marine fish eggs, due to their abundance and high nutritional value. Parental care ends when the egg case is released from the body, so the embryo relies on its tough, leathery exterior as its only source of protection. Some gastropods are known to feed on egg cases by boring into the exterior. Sharks are also common predators of egg cases. References External links http://www.glaucus.org.uk/Mermaid.htm Cartilaginous fish Fish reproduction Ichthyology Articles containing video clips