Baleen is a biological structure that replaces teeth in the mouths of Mysticeti, or baleen whales. This system of fringed plates allows these large animals to sustain themselves through filter feeding. Understanding the texture of baleen requires looking at its dual nature: the rigid plate structure and the soft, fibrous inner fringe.
The Physical Sensation of Baleen
The overall sensation of baleen is a striking contrast between stiffness and flexibility. The main body of each plate, which can reach several meters in length, is rigid and strong. This part has been compared to the material strength of buffalo horn, providing a firm foundation for the filter-feeding apparatus.
The sensory experience changes dramatically at the inner edge of the plate, which faces the whale’s tongue. Here, the material frays into a dense, tangled mat of bristles or “baleen hair.” This inner fringe feels fibrous, much like a thick, stiff brush or coarse straw. This mat allows water to flow through while trapping small prey.
What Baleen is Made Of
The material responsible for baleen’s unique structural properties is keratin, a fibrous structural protein. Keratin is the same protein that forms the primary component of human hair, fingernails, and the horns of terrestrial mammals. This composition provides baleen with a necessary balance of both strength and resilience.
The plate itself is a mineralized, tough, alpha-keratin material that must withstand intense mechanical pressure during feeding. Baleen is highly ductile when hydrated, meaning it is strong yet flexible enough to bend without breaking. The density and degree of calcification in the keratin varies among species, contributing to differences in stiffness and filter performance.
How Whales Use Baleen to Feed
Baleen whales employ this structure as a massive sieve to consume tiny prey, such as krill, copepods, and small fish. The feeding process involves the whale taking a huge gulp of water and prey, often expanding its throat using specialized grooves. Some species, like rorquals, use a high-speed lunge to engulf food, while others, like right whales, continuously skim with their mouths open.
The whale then uses its massive tongue to push the water out of its mouth and through the baleen plates. As the water escapes through the spaces between the plates, the dense, bristly fringe acts as a filter, trapping the food inside the oral cavity. The whale then scrapes the captured prey off the inner fringe with its tongue and swallows the food whole.