In this activity, the connection between terrestrial mammals (humans) and open water marine mammals (orcas) is investigated through the comparison of traits. Students will compare and contrast features of orcas with themselves.
Orcas, also known as killer whales, live mainly in deep, open ocean water, but can be found close to the shore for some activities. While orcas are smaller compared to other whales, they are very large compared to land animals. Some adult males can have having dorsal fins up to 2 metres tall!
Orcas:
- are toothed mammals
- are the largest members of the dolphin family
- breathe air, are voluntary breathers, and need to be at least half awake at all times to breathe
- live in families called pods, led by females
- give birth at sea to live calves
- can live up to 70–80 years
- eat 50–150 kg of food a day, depending on size and energy needs
- have a thick blubber layer of fat under their hairless skin to enable them to keep up their body temperature in BC's cold coastal waters
- communicate with each other through vocalizations.
Each Orca pod has its own collection of calls (dialect), which functions like a language.
Orcas use calls to find each other in the water, but how does a visual predator find their food in dark murky waters? Orca find food using echolocation; a series of high-pitched clicks. Orcas send out clicks vocally. The clicks bounce off objects and come reflected back to the orcas' to sense through their fatty "melon" brow and lower jaw. By using echolocation orcas can determine sizes, shapes, and distances of objects, as well as communicate with each other without sight.
Southern resident killer whales, found in the waters of southern British Columbia, are protected as a Species at Risk with the classification Endangered because there are less than one hundred whales in the population.
Issues affecting the Southern resident orcas include:
- underwater noise that causes communication interference and sound pollution
- declining fish populations for food
- toxic exposure through water pollution
- surface impacts such as commercial shipping, fishing, whale watching and pleasure boating