Get the lowdown on seals

I admit: I’m no expert on seals. Like you, I know what they look like, I mean I’ve seen quite a few, mainly as a kid on my annual seaside holiday to North Norfolk. But I don’t really know much about them. Sound familiar? So, come with me on a journey as I delve deeper into their mysterious world.

Common or grey?

There’s just two resident seal species in the UK – the common (on the left here) and the grey (on the right). Confusingly, the common seal is actually less common than its bigger cousin the grey! Across the pond in America, common seals are actually known as harbour (ok, harbor) seals, and that’s a good name to describe its habits of living close in to land for most of the year.

Common seals are smaller with snub-noses, and there is very little difference between males and females, although males may be slightly larger. By contrast, the male grey seal is considerably larger than the female. Greys have a distinctive long snout – I’ve heard them described as having ‘Roman noses’. In fact, its scientific name (Halichoerus grypus) means ‘hook-nosed sea-pig’, a bit harsh perhaps, but it certainly does describe their appearance!

Coming ashore

Because seals are evolved from land carnivores and, unlike whales and dolphins haven’t evolved ways of giving birth at sea, they must return to land to give birth to their pups. Between September and November, grey seals haul out on rocky shores to have their fluffy, white-coated pups. They’ll then spend around three weeks ashore.

Common seals do it differently, coming ashore on sandy beaches and intertidal areas from May through to July. Their pups are more readily adapted to a marine life. They shed the white coat before birth and are born with well developed hind flippers, meaning that they have the ability to swim within just a few hours of birth. The mother and pup then spend most of their time together in the sea.

Diving

Here’s what I thought was the most interesting thing I discovered about seals.

Now, when you or I head under the water, we must take a deep breath – as do whales and dolphins. Seals however, do the opposite. They breathe out before diving, leaving very little air in their lungs. Whilst this seems counter-intuitive, it’s just one of many adaptations to a marine life.

Because there is very little oxygen in their blood, there’s no point in pumping it round their body. So, to overcome this a seal’s heart slows down, both in the number of beats and the strength of the beats. So when a seal is hunting underwater, it’s not breathing, and barely beating it’s heart! The oxygen is actually stored in it’s muscles, which are specially adapted. Upon returning to the surface, it must then inhale air quickly to recover. That’s amazing, isn’t it?

Sleepy seals

Seals can sleep in the sea, I found out. However, this can present a problem – they naturally sink! As I’m guessing that’s a bit of issue they normally haul out.

Can I see seals on RSPB reserves?

In short, yes! I’ve actually seen a common seal at our Ouse Washes reserve. Yes, that’s right, a reserve in land-locked Cambridgeshire! Admittedly, I uttered ‘what on earth is that?’ when I first saw its head poke out of the water. But, it turns out, common seals are not actually uncommon in fresh water rivers and have been known to travel several hundred miles upstream. Grey seals, on the other hand, are much less likely to enter rivers.

There’s a whole load more reserves where you’re much more likely to see seals though, let’s be honest, Cambridgeshire isn’t a seal hotspot!

Find out more...

Well, I’ve certainly learnt a lot about seals. Despite being mammals like us, they are brilliantly adapted and evolved for their mostly marine life.

Do you have any seal stories? Or have you ever seen one in a usual place? Let us know by commenting below.