1. Martens differ from other animals in the weasel's family by being excellent climbers. They spend the day sleeping in the trees and have cats' ability, being able to make jumps through the branches of the trees as easy as the squirrels. Amongst the martens of the Old World, beech marten is the most widespread in Europe and Central Asia and has a white spot under the chin that prolongs to the uper fore limbs. Pine marten, which has a distinctive yellow-orange spot under the chin, is restricted to Europe and western Asia but goes further to the north. Pine marten inhabits dense forests, but the beech marten can enter villages and cities (where it feels safer), and prefers rocky area, forest edges, parks and gardens. Still, as they are nocturnal, they are hard to spot. Pine marten is 80 cm (2.6 ft) long; the beach marten 60-70 cm (2-2.3 ft).

In Siberia, the pine marten is replaced by the sable. Yellow-throated marten is found in east and southeastern Asia.

The American marten inhabits especially Canada, being found from Alaska to Newfoundland. It is the most arboreal marten. The fisher is the largest marten; it lives especially in Canada and has a smaller range.

Martens have short, but powerful and agile limbs, that allow them to make long jumps while running. They chase their prey in the trees, and can catch squirrels. During the winter, when prey is scarce, they can hunt more on the ground. The beach marten is a worse climber than the pine marten. Marten have curved, long but non-retractile claws.

The fishers can hunt beavers, porcupines (by turning them on the back), and even American martens or deer, if trapped in the snow.

2. The European polecat lives mainly in Europe, while steppe polecat and marble polecat inhabit Eastern Europe and Central Asia. The European polecat lives from sand dunes and ravines to farms, hills, forests and it even shelters in abandoned buildings during the winter.

The marbled polecat digs its burrow by itself, using its large claws of the fore limbs. The domestic ferret is a type of albino half tamed European polecat. It is used for hunting rabbits and rats. It was probably domesticated in the Middle East about 3,000 years ago and introduced in Europe from North Africa by the Romans. The North American black-footed ferret is more related to weasels than to the polecats.

3.Martens mate in July-August. Polecats can have up to 10 (and even 18) newborn pups, a record in the weasel family. Gestation lasts 40-65 days in the case of polecats, but martens have delayed implantation and birth can take place 200-300 days after mating (the proper gestation is 2 months). Martens use crows' and squirrels' nests to give birth, but they can also nest in tree hollows located high into the trees or protected dens. A marten litter is of 3-8 offspring, with an average weight of 30 grams.

Polecats climb rarely, and make nests on the ground. The newborn are blind and their eyes open in 30 days. They are weaned by the age of 7 weeks (8 weeks in the case of the martens). At the age of 44 days, marten offspring get out of the nest. To the end of the summer, the young martens look for a territory close to that of the mother.

4.Martens mark their territories using the secretion of the anal glands. The powerful scent is left on stones and tree trunks. Marten fur is extremely appreciated in Europe, and the animal went extinct in many places because of this. Sable fur is one of the most expensive in the world, and the animal is farmed.

Martens hunt small mammals, birds (up to pheasants), bird eggs (they can carry them into their mouths), insects, reptiles, rarely fish and even plants. They hunt be useful by destroying rodents, but the beach marten will take domestic birds, including pigeons. Martens are attacked by prey birds, wild cats, owls, foxes and dogs.

5. When attacked, the polecat emits the stenchy secretion of its anal glands, just like its relatives, the skunks.