Paul Naylor looks at the egg-laying habits of two well-known British shark species
UKDIVING CRITTERCONFIDENTIAL
Catsharks and their eggcases
Smallspotted catshark- Scyliorhinus canicula Nursehound, bull huss( greater-spotted catshark) – Scyliorhinus stellaris
Young Nursehound among seagrass in the Fal Estuary
Paul Naylor looks at the egg-laying habits of two well-known British shark species
Like many keen divers, the underwater world is never far from my mind, even when I’ m not diving. While I was walking on the coast path next to the Solway Estuary recently and found a bunch of dried and empty catshark egg cases blown up onto the grass, I started thinking about these wonderful animals and decided to focus on them for Critter.
The small-spotted catshark( often previously called a‘ dogfish’) is one of our smallest sharks and the one generally encountered most by UK divers. While perhaps not as glamorous as their large shark relatives, their habits can be just as intriguing. Typically found resting on the seabed during the day, they do most of their cruising and hunting at night. Crabs are common prey among a varied diet and, handily, will often then be out and about.
Studies in some locations have shown that, during their nightly feeding excursions, the sexes go in opposite directions. This serves to help females stay away from aggressive courting males, except when needing to mate. The groups of females sometimes found resting in caves or gullies on the seabed are thought to act as a refuge for the same reason. Research, aided by the recognition of individuals from their spot patterns, has also shown that some catsharks individuals are inherently more sociable than others. As always with behaviour, the more we look the more we learn!
When laying their eggcases, which can be
Nursehound eggcase tied to seaweed( photo taken by dipping my waterproof compact into a shore pool)
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Lucky find, a young Nursehound showing key features such as paler eyes and prominent nasal flaps