By Lauren Moriarty
National Dolphin Day celebrates these social and intelligent marine mammals. Dolphins are cetacean mammals that are related to whales and porpoises. They are fascinating creatures which are very social and playful. Dolphins hear frequencies through hearing sensors in two small openings on both sides of the head. They “hear” underwater through the lower jawbone which conducts sound frequencies to the middle ear. Dolphins hear with a frequency of up to 160 kHz, compared to humans whose hearing can range in frequency from 0.02 to 20 kHz. They are brilliant animals and can learn not only as individuals, but they can also pass their new knowledge on to other pod members. Dolphins are known to bite when they are angry, frustrated, or afraid. Dolphins have saved many human lives on many occasions, often from shark attacks. Great white sharks are a threat to dolphins, however, in groups are often safe. Dolphins also have the advantage of speed, as they can swim faster than most shark species.
Resident dolphins that can be spotted along our coastal area in Plettenberg Bay and Nature’s Valley are the Bottlenose, Long-beaked Common, and Humpback dolphins. Bottlenose dolphins which we are more familiar with and which are more commonly noticed along our shores, swimming in waves and playing, generally spend their time closer inshore, travelling or resting in the surf zone because it is thought to be a safe zone for them to be in. They are fast swimmers and very active, often seen jumping out of the water, playing, and slapping their flukes on the water’s surface. Bottlenose dolphins got their name from their short beak and can grow up to 2,5 m in length. The Common dolphins are found further offshore. However, if you are on a trip out to sea you might be lucky enough to encounter a pod of Common dolphins, this is a fascinating sight as they often travel in large groups reaching hundreds of individuals. The Humpback dolphin seen closer inshore, living in shallower coastal waters are considered shy creatures. They travel in tiny groups and are not always seen. They can be noticed by the hump on their back fin when emerging from the water’s surface.
Dolphins play an important role in keeping their environment in balance. They eat mainly fish and squid, and even some smaller shark species. However, human interaction does have an effect, especially with inshore shallow dwelling species where habitats overlap. Marine pollution is a constant threat with plastic pollution, discarded fishing material and nets. It is so important to not only celebrate these beautiful marine mammals but help raise awareness for their protection.
Fun facts about national dolphin day:
- Common species to be seen in our areas are the Bottlenose dolphin; Common dolphin; and Humpback dolphin, however, there are 39 other dolphin species that can be found off the coast of South Africa.
- Dolphins chew their food. They use approximately 100 teeth-like fishhooks to snag food and swallow it whole.
- Their young can stay with their mothers sometimes for eight years after birth.
- Orcas or Killer whales are classified as a dolphin.
- The Orca is the largest dolphin. Hector’s dolphin and Franciscana dolphin are two of the smallest in the world.
Visit our website for more information on our Marine Tourism project and our resident marine mammals.