Baleen is an elastic horny material made up of keratin, the same fibrous protein material found in fingernails, hair, and feathers. Baleen is used in a filter-feeding system that hangs in rows from the roof of the mouth of a baleen whale. The whale pushes a scooped-up mouthful of water, partly shuts its mouth, and then uses it tongue to push the water through the “hairy” baleen. The baleen acts as a strainer/filter to catch small animals, such as krill, which are numerous tiny arthropods that float in sea water.
Partial view (100-cm-long) of piece of baleen from an eastern Pacific whale.
Note: the other major group of whales are the toothed whales (e.g., killer whale), and they have only one blowhole.
Some gastropods, all of which have tiny limpet-like (inverted “V” shaped shells), can live in decaying baleen. There are four known families of these gastropods: pyropletids, cocculinids, osteopeltids, and neolepetopsids. A recent paper by Marshall and Walton (2021), which is given at the end of this blog post, described an osteopeltid limpet gastropod that was found to feed on baleen off the coast of New Zealand, in waters of 377 to 1042 m depth. How this gastropod and other ones like it metabolize the tough and essentially inert baleen is unknown, but it is probably related to the action of symbiotic bacteria within the gastropod gut. The shape of this gastropod is illustrated below.
Oval outline of the shell of the deep-sea osteopenia gastropod limpet Baleenopleta rotunda, top view, 12.5 mm diameter. Top view, height 4.5 mm of same B. rotunda specimen as shown below.
Side view, height 4.5 mm of same B. rotunda specimen as shown above.
Numerous minute specimens (small ovals) of Baleenopleta rotunda in living position in the narrow spaces between the “ribs” of a 110-cm-long baleen “frond.”
Key Reference:
Marshall, B.A. and Walton, K. Jan., 2021. Baleenopelta rotunda, a newly discovered limpet from decaying baleen from New Zealand. Molluscan Research. Published online.
No comments:
Post a Comment