Dogfish or Spotted Catshark
This is the commonest shark in Harris waters. Like all sharks it has no bones; its skeleton is made of cartilage instead (the bendy stuff in your ears and the end of your nose is cartilage). Unlike bony fish it has eyelids, and lacks gill covers – each of the 5 gills on each side of its head has its own gill slit where the water is exhaled. You may find a dogfish egg case which are sometimes washed up, commonly referred to as a ‘mermaid’s purse’. These large yolk-filled eggs are laid with long soft tendrils at each corner which are wrapped around seaweed plants – these soon harden and provide an excellent strong anchorage for the egg while it develps.
Like all sharks, dogfish produce very few offspring each year. This means they react badly to overfishing, and a population will take a long time to recover if too many fish are removed from the sea.
Dogfish (Photo: Sue Scott)
The dogfish is the smallest and most numerous shark to be found around our coasts
Dogfish Egg (Photo: Paul Tyler)
Dogfish attach their eggs to seaweed to stop them drifting around.
Dogfish Embryo (Photo: Sue Scott)
Empty egg cases are frequently washed up (and are often referred to as ‘memaid’s purse’ The developing baby dogfish can be clearly seen inside its egg case.
by Paul Tyler