The Development of Swell Sharks

Swell sharks are pretty spectacular cartilaginous fish. True to their name swell sharks have the ability to puff up by sucking up air or water into their stomach allowing them to appear bigger to potential predator or threat. But how do these incredible sharks begin their life? In an egg of course! Female swell sharks are oviparous, meaning they produce eggs that develop and eventually hatch outside of the body. Females can produce as many as 4 eggs at a time and typically lay them among rock and algae. Within the egg case a large yolk provides 100% of the nutrition to the developing embryo. During their early stages of development they even posses external gills! Swell shark pups typically take about 9 to 12 months to fully develop – this time frame is at times dependent on the water temperature. In order to help themselves in the hatching process swell shark pups will develop two rows of enlarged dermal denticles on their back while they are still in the egg case. These enlarged denticles aid in the shark pushing itself out of the case! When they first emerge from the egg case pups are pretty tiny as they are only about 6 inches in length. These pups are fully independent once they hatch and must find food, such as benthic invertebrates, on their own.

According to ancient legends empty egg cases of swell sharks were considered to be mermaid purses.

Written By: Alex Feltes