Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player

 

Search in the Encyclopedia

Cetaceans

breathing method:

via lungs, stores oxygen in muscles

size and weight:/

largest cetacean (blue whale): maximum 33 meters and 170,000 kilograms
smallest cetacean (porpoise):  maximum 1.90 meters and 60 kilograms

communication:

baleen whales low-frequency sounds
toothed whales echolocation

enemies:

humans (hunting, pollution, noise pollution) and diseases

food:

baleen whales small marine animals, plankton and small shellfish
toothed whales fish, cuttlefish

  • Dut: walvisachtigen
  • Eng: cetaceans (whales, dolphins, porpoises)
  • Fren: cétacés (baleines et dauphins)
  • Ger: Walartige
  • Lat: Cetacea
  • Dan: Cetacean
, Most drawings: Frits Jan Maas

Cetaceans

Cetaceans is the official name for the whale family. When you hear the word 'whale', you usually picture a giant animal. However, porpoises which are only 1.5 meters long also fall under cetaceans. The predecessors of the cetaceans lived on land. During the Tertiary period (around 50 million years ago), a group of predator-like mammals moved to coastal regions. They slowly adapted to swimming in the sea. They were animals without back legs, but had fins and a wide flattened tail.

  • Teeth or seaves
    Killer whale, marijke de boer

    Cetaceans can be subdivided into baleen whales and toothed whales. Most baleen whales are gigantic. They have an enormous toothless mouth. Instead of teeth they have baleen, which are plates made from horn-like material and hang in rows in the palate of the upper jaw. The whales use these baleen plates to filter out their food. Most of these whales live off of krill: shrimp-like animals found in plentiful amounts in the open sea. They will also consume small fish such as herring. Toothed whales are generally much smaller than baleen whales. Only sperm whales are comparable in length with baleen whales. Dolphins and porpoises are also toothed whales. They eat primarily fish or squid.

  • Distribution in the North Sea
    Sperm whales, marijke de boer

    Porpoises, dolphins and larger whales are difficult to observe in the open sea because they swim under water. Large whales are rarely ever observed in the North Sea. Only the minke whale, the smallest baleen whale (8 meters), is regularly seen in the northern North Sea. In recent years, since the millennium, humpback whales have also been spotted regularly off the Dutch coast. These animals seem capable of swimming in shallower waters, particularly when hunting large schools of fish. If a sperm whale or any other large whale species ends up in the shallow southern North Sea, then it is usually a case of a lost or sick animal. Their chances of survival are slight and they eventually wash ashore somewhere. Because the North Sea is warming due to climate change, the currents in the ocean are also changing. Therefore, it is quite possible that more whales as well as more species of whales will end up more often in the North Sea.

  • Dolphin rehabilitation
    porpoise on Texel, ecomare, salko de wolf

    Live large whales that wash ashore are difficult to rescue. They are too large and too heavy and collapse under their own weight. There is only a chance of helping them after stranding if they can float during the following flood. Specialist can then try to lead them to deeper waters. Porpoises and dolphins are easier to rescue but even these animals are much more difficult to care for than seals. Nevertheless, the organization SOS Dolphin, located at the Dolphinarium in Hardewijk, tries to rehabilitate dolphins and porpoises as often as possible.

  • Exceptional cetaceans along the Dutch coast
    Beluga, Sytske Dijksen, www.fotofitis.nl

    Every once in awhile, very rare whales are spotted along the Dutch coast. Close to the shore in the North Sea, several bones have been found from the gray whale and the North Atlantic right whale. These bones are proof that these species of whales swam here probably up to the Middle Ages. Sometimes, a lost beluga from the far north is seen in the North Sea. One swam in the river Rijn in 1966. In 1980-1981 and 1984, one was seen at the mouth of the Schelde and Eems. Belugas are inhabitants of river mouths in the North Pole region. Even though it is extremely unusual to see them in our area, it isn't strange that they are found in or close to rivers. In 1912, a narwhal died in the Zuiderzee. This narwhal probably wandered from the far north. The blue whale, the pygmy sperm whale and the pair of false killer whales that once beached along the Dutch coast, had wandered in from the Atlantic Ocean.

    DatePlace and details
    1840 Blue whale - Hoek van Holland
    11 March 1912 Narwhal - Zuiderzee near Elburg
    13 December 1925 Pygmy sperm whale - Noordwijk aan Zee
    28 November 1935  False killer whale - IJmuiden, 2 animals
    From various sources, including Chris Smeenk (Naturalis)