The marine waters around the province are considered boreal, or sub-Arctic, in nature. A great deal of the coastline is rock-strewn, allowing an extensive variety of plant and animal life to thrive. The leading plants of the shoreline are the large brown seaweeds, such as bladder, forked and knotted Wracks, and winged and sugar kelps, though there are also a number of red and green seaweeds present. Common animals of the seashore region include barnacles, tortoiseshell limpet, common periwinkle, blue mussels, sea anemones, sea slugs, sea urchins, starfish, and rock crabs. The deeper waters are home to a variety of fish, such as Atlantic cod, sculpins and cunners, halibut, haddock, sharks, and marine mammals, such as dolphins, porpoises, and whales. Whales seen off Newfoundland include Pilot whales, minkes, sei whales, fin whales and humpbacks. Harp and hooded seals are usually found in the spring, giving birth to their young on coastal ice floes.