Bird feet and legs

The foot of the birds has a number of structural characteristics to the foot of the other vertebrates. The number of toes varies between two and four species-specific, the latter is the rule. The bird foot is mostly featherless and covered with horny scales. At the end of the toe claws are formed. In birds of prey both feet are also referred to as " catch ", since they are used for grasping and hitting the prey.

Basic structure

In birds, the ankle ( tarsal ) is constructed differently than in mammals because the bones of the original series proximal bone of the ankle joint with the tibia to the tibiotarsus and gradually grow the distal row with the metatarsal to the tarsometatarsus ( " walking legs "). Instead of a composite tarsus a simple, known as intertarsal bone connection is thus constructed.

The metatarsal or "run" is supported by the metatarsal already mentioned. In birds, only a single walking leg is independent of the number of toes are formed. This has in the upper part on the rear side, a bead knöchernden the Hypotarsus, with grooves or channels for the tendons of the flexor muscles of the toe.

The number of toes in birds varies depending on the type of between two and four. Most birds have four, only a single species, the African ostrich has only two. The number of phalanges ( phalanges ) is by one unit greater than the atomic number of each toe; Thus, the first toe has two members, the second of three, and the third and fourth four- five.

Toes arrangement

After the number of toes, and their arrangement on foot one distinguishes between different types of bird foot.

• The anisodactyle toe arrangement is the most common and can be found for example in all songbirds. It shows the first toe to the rear and the other three to the front.

• The second most common form of birds within the zygodactyle arrangement. In this form, the first and fourth toes are directed to the rear, the second and third forward. The Zygodactylie example, is typical of parrots, owls and cuckoos.

• Heterodactyle the arrangement corresponds to the zygodactylen, but here instead of toe 4 toe 2 is directed to the rear. In this form, therefore showing the first and second toe to the rear, the third and fourth forward. Such an arrangement is found only in the trogons.

• In the second and third toe syndactyly which are partially grown together, this can be found in the kingfishers and other representatives of coraciiformes.

• When pamprodactylen arrangement Show all 4 toes forward. The first and fourth toe can thereby move freely back and forth. Most sailors have such a toe position, allowing them to cling to vertical structures.

• If the first toe is missing completely is referred to this as Tridactylie. A " Dreizehigkeit " occurs ( emus, rheas, cassowaries ), bustards, pelicans and many Regenpfeiferartigen many ratites.

• The Zweizehigkeit of the ostrich is called Didactylie.

Skin formation

The bird foot is mostly featherless and covered with horny scales. The last phalanx carries mostly a pointed horn cover in the form of a claw. Between the toes skin folds are formed in the form of webbed in waterfowl.