IN THE SEA
The Irish Sea is made up of many underwater marine habitats. There are underwater cliffs, rocky reefs, kelp forests, sea grass, maerl and horse mussel beds. In turn, these habitats support great communities of thousands of different species of marine plant and animal. It may seem difficult to get excited about a world which is mostly hidden to us, but it is vital we keep our seas healthy. Marine habitats play a central role in our well being – from helping to combat climate change, to providing resources for construction, to supplying us with food.
BETWEEN THE TIDES
Although you may not be able to get to see some of our deep water species, you can get a glimpse into the underwater world at our coastlines. This rich sea life is most accessible to you at low tide, around our rocky shores. Why not go on a rockpooling adventure to see what you can find? Tidepools high on the shore are difficult places to live. The temperature and saltiness of the water fluctuate widely. Animals and plants living here have to deal with bird predators at low tide and fish or crab predators at high tide. Only a few tough species such as transparent shrimps and bright green seaweeds thrive here. Mid shore pools are more complicated ecosystems. Red, green and brown seaweeds provide homes for a rich variety of animal life. You may find beadlet anemones, shore crabs, hermit crabs, shrimps and cushion starfish. You will certainly see limpet, periwinkle and dogwhelk. Fish such as gobies, blennies, butterfish and scorpion fish also live here. At the extreme low tide mark you might find lobsters, large edible crabs, sea urchins, starfish and the beautiful dahlia anemone nestling amongst the kelp.
In summer, the Irish Sea is home to one of the world’s largest concentrations of basking sharks, congregating especially around the Isle of Man. These wonderful creatures are the second largest fish in the world. They can grow to over 11 metres long and weigh 7 tonnes. Basking sharks are plankton-eating filter feeders that are harmless to humans. They swim slowly just below the surface of the water, feeding on the plankton which concentrate there. They look like they are ‘basking’ in the sun. A basking shark can filter the amount of water needed to fill an Olympic sized swimming pool in just one hour!
Several species of marine mammal are seen in the Irish Sea. The easiest to spot are the grey seals, as they haul themselves out on land to rest and to give birth. They spend about 80% of their time in the sea, however, and are incredibly quick and graceful underwater. Powerful swimmers, they can easily swim across the whole Irish Sea, feeding and resting in different spots along the way. There are also many species of whales, dolphins and porpoises in the Irish Sea. The most commonly sighted are harbour porpoise, bottlenose dolphin, common dolphin, Risso’s dolphin and minke whale.
Believe it or not, good old fashioned mud is one of the most important habitats of the Irish Sea.
Whilst they may not be much to look at, these squishy grey plains are host to an astonishing concentration of life. The spectacular flocks of wintering waders and wildfowl found here in internationally important numbers are good indicators of just how much there is living in this mud. So what is it they’re after? Living on or just below the surface of the mud is a huge concentration of invertebrates that thrive in the reduced salinity of the estuary. These include ragworms, which turn their entire head inside out to snare prey in their vicious looking jaws and sludge worms, which can appear blood red as they use haemoglobin to transport oxygen, just like you!
Where it is mixed with just a little sand, Irish Sea mud will support beautiful sub-marine meadows of sea-grass. Sea grasses are true plants, unlike seaweed which are algae, and they undergo their entire lifecycle under the sea, from flowering to pollination and seeding. Sea grass meadows provide sheltered nursery grounds for many of the flatfish species that characterise the Irish Sea as well as harbouring their own unique complement of invertebrate fauna.
So next time you look out across a seemingly desolate stretch of dull mud, remember that it’s not so boring under the surface!