baleenplaten

Baleenplaten, known in English as baleen plates, are keratinous structures that form the baleen apparatus in the mouths of baleen whales (Mysticeti). They hang in two symmetrical rows from the upper jaw and function as a filtering system for suspension feeding. The plates are made of keratin and bear a comb-like fringe of baleen fibers along the inner edge, which traps small prey while allowing water to pass through.

Each baleen plate grows from the gumline and lengthens over time; wear from feeding is accommodated by continual growth at the base, so the plate remains functional as the whale ages. The baleen fringe is composed of hair-like fibers that create a dense, flexible sieve, varying in density and length among species.

Feeding relies on taking in large volumes of seawater and prey, then closing the mouth so that water is expelled through the baleen while prey is retained on the fringe. The trapped material is then moved to the throat and swallowed. Baleen whales thus rely on a low-energy, high-throughput filter-feeding strategy, enabling them to exploit abundant planktonic prey.

Evolutionarily, baleen plates are a defining feature of Mysticeti, reflecting a transition from toothed ancestors to a keratinous, filter-feeding system. The fossil record includes transitional forms showing teeth in early mysticetes and the gradual emergence of baleen.

Historically, baleen was harvested and sold as “whalebone” for uses such as corsets and other flexible materials, contributing to past whaling industries before modern conservation measures.

Baleenplaten vary in size and arrangement among species, contributing to differences in feeding behavior and prey selection within baleen whales.