A paper on the classification of cat shark eggs, a joint research project with the Consulate-General of Japan, has been published.

A paper on eggshell characteristics of catsharks, a joint study conducted by the Consulate-General of Japan in Australia and the Commonwealth Scientific and Industrial Research Organisation (CSIRO), was published on the website of the British academic journal Journal of Fish Biology on October 2024, 10. This paper compared the egg characteristics of nine of the ten species in the catshark family whose egg shapes are known, and found that they can be classified into three groups based on their characteristic traits.

CSIRO (official name: Commonwealth Scientific and Industrial Research Organisation), which published the joint paper this time, is a very large national organisation in the Commonwealth of Australia. Our aquarium boasts the largest number of shark species in Japan, and currently keeps five species of cat sharks. This time, we were asked by CSIRO to carry out the joint research.

Bullhead shark
port jackson shark
horn shark
striped shark 
* Raised in the back yard
crested bullhead shark 

The museum provided tissue samples for DNA analysis and eggshell specimens from the cat sharks it is keeping to the CSIRO in Australia.

The eggs of the cat shark family are famous for their unique, screw-like shape. The shape varies depending on the species, with some having tendrils (vines) (e.g., the striped cat shark), some having no tendrils and a wide, fold-like protrusion (e.g., the horn shark), and some having no tendrils and a narrow, fold-like protrusion (e.g., the cat shark).

Striped jackal shark eggs
horn shark eggs
Cat Shark Eggs

In this study, we conducted a detailed analysis of the eggshell shapes of nine species of the cat shark family and compared them between species, enabling us to numerically clarify the characteristics of each species.

We plan to introduce the results of our research, including this presentation, to everyone through shark exhibits and events. We will continue to actively collaborate with aquariums and research institutions both in Japan and abroad, and hope to use this knowledge to help shed light on the still mysterious ecology of sharks, and to contribute to nature conservation.

[Special Program] Shark Special Tour

Aqua World Oarai will be holding a special program called "Shark Special Tour" every day from October to December, where you can experience feeding the sharks. You can see the behind-the-scenes of shark breeding with explanations from the zookeepers! For more information, .