page_title: Spix's disk-winged bat
section_title: Disks
hierarchical_section_title: Spix's disk-winged bat / Description / Disks
caption_attribution_description: English: Suctorial Disks in Thyroptera tricolor, Chiroptera from 1911 Encyclopædia Britannica
context_page_description: Spix’s disk-winged bat, is a species of bat in the family Thyropteridae. It is native to the Americas from Mexico to Brazil. The most prominent anatomical feature of this bat, which distinguishes it from other species, is the disks on its thumbs and hind feet. These circular disks act as suction cups, allowing the bats to cling onto and move along smooth surfaces.
context_section_description: Unlike most bats, T. tricolor clings head-up from its roost. This phenomenon is observed in six bat species in two genera, Thyroptera and Myzopoda. The former are known as disk-winged, and the latter as sucker-footed. The two groups represent an occurrence of the parallel evolution of a feature, but the two forms of adhesive anatomy are utilized differently.
  The disk-winged bat seeks a bud of rolled-up leaves with the opening at the top. It clings head-up to the smooth inner (ventral) surfaces of the leaves. Plants with this leaf morphology include Heliconia and Calathea species. This manner of roosting is said to facilitate rapid escape in the event of a potential disturbance. The bat’s disks take the shape of concave cups, and are supported by an internal cartilaginous plate. The flexor pollicis brevis muscle attaches to the plate, such that contraction of the muscle alters overall disk shape, creating suction. In order to maintain the integrity of the disk the bat grooms it frequently by licking it. The disk also contains abundant sweat glands, maintaining a moist surface.
  The Madagascar sucker-footed bat (Myzopoda aurita) has a similar sucker anatomy, but produces suction differently. It uses its flexor muscle to change the shape of the disk when detaching from a surface. It also uses sweat lubrication to produce wet adhesion as the main mechanism, rather than suction. It can only attach head-up, while the disk-winged bat can cling at any angle. M. aurita can concurrently make contact with both its adhesive organ and thumb claw, whereas T. tricolor cannot. This may be due to the difference in the anatomy of the muscle insertions and the actions they bring about.
caption: Illustration of the disks
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