So if you were wondering which are the largest seals in the whole world, the answer is the Elephant Seals! There are two different types of Elephant Seal – those that live in the northern hemisphere, and those that live in the southern hemisphere. These impressive animals get their name from not only their huge size, but also the elephant-like “trunk” or proboscis that protrudes from the face of the males. The main purpose of this appendage is for breeding displays, and in sexually mature males, the proboscis will fill with blood and air, and amplify the loud roar they make at rival males. These deep bellows fill the air at a breeding colony, along with the clack of two seals slamming their bodies into one another in a mating competition we will talk about in a second. This week we are focusing on the smaller of the two species, the Northern Elephant Seal (Mirounga angustirostris).
M. angustirostris itself means to have a narrow beak, which refers to a comparison with the Southern Elephant Seal. However the northern species actually has a slightly longer trunk, and can still grow up to a whopping 5 m long and weigh 2,200 kg (3 m and 800 kg in females)! They are enormous true seals, unrivalled in size by most other pinnipeds. Northern Elephant Seals are found from the Aleutian Islands off Southern Alaska, right down the coast of the North Pacific Ocean as far as Baja California in Mexico. Historically, these animals were slaughtered in their thousands for their blubber, so much so that they very nearly went extinct by the end of the 1800’s. In this way they are a conservation success story. From an estimated 20-100 remaining individuals in 1910, they have since had an amazing recovery, aided by government protection and the allocation of a dedicated marine reserve. Today, worldwide there are estimated to be around 239,000 individuals.
The males and females of M. angustirostris are extremely sexually dimorphic, which means they are very different from each other. As we have said, the males have large ‘trunks’ on their faces, which the females lack, and they are also almost twice the size. Males engage in aggressive battles on the beach during the breeding season to establish dominance over a harem of females. This can result in a lot of blood and physical damage, and older males may often have many scars from the altercations. For this reason, males also have a thick, pink-tinged neck which helps protect them from the teeth and strong jaws of their rivals. When a male wins a battle for a beach, he may engage in mating behaviour with over 50 females! This leaves the younger, inexperienced, and weaker males without access to ovulating females. Female seals have been known to be killed by over-zealous males, and it is sadly not uncommon for pups to be trampled and squashed to death during the scuffles. The pups themselves are born with a black fluffy coat, or lanugo, and will be nursed for around a month with extremely fat-rich milk, before moulting into a silvery juvenile coat and beginning life solo. During the final development period they will travel in groups with their peers and start to learn to swim and forage effectively. Adult M. angustirostris are excellent divers who regularly reach 500-1000 m depths, sometimes deeper. This is essential for collecting the twilight zone fish and squid that make up their diet.
All in all, the Elephant Seal really is a sight to behold, an example of the weird and wonderful adaptations that exist in the animal kingdom to ensure survival in extreme locations. Their sheer size is absolutely phenomenal, and the battles truly heart-stopping moments to witness in the flesh. Thank goodness we had the foresight to protect this species, ensuring that they are still here to be marvelled at today. And this is where we’d like to leave off today.. thinking about how important it is that we protect the wonderful species in nature for future generations to experience. Long live the Elephant Seal!