The skin of vertebrates can present different types of differentiation, which help the performance of its functions. The main cutaneous differentiations are scales, hair, feathers, nails, claws, hooves and horns, as well as various types of glands. Scales are structures in the form of flat plates, which are arranged on the integument as a protective armor.

The best known bryophytes are the liver and moss. The liverworts are both aquatic and terrestrial, and their stalk is an extremely thin blade. Its stalk is very reminiscent of a superior vegetable: it is erect, growing from the ground. Hepatic In mosses, as indeed in all bryophytes, there are two somatic adult generations with totally different aspects that alternate in a reproductive cycle (gametophyte and the sporophyte).

Often, we do not notice the presence of those animals with bodies of strange shapes and varied colors that live around us, fly over our heads or those that move near our feet. Most of these beings are formed by arthropod animals. This group includes animals such as spider, fly, crab, centipede, snake louse, shrimp, scorpion, bee, among many others.

The classification of protozoa is based primarily on the types of reproduction and locomotor organelles. The locomotion is done by ciliary, flagellar, emitting pseudopods and even by sliding the whole cell body. In some ciliates there are, instead of the cytoplasm, contractile filaments, the myonemes.

Scientists have identified a part of the brain that appears to be unique to humans. The brain region, called the lateral frontal pole of the prefrontal cortex, was described on January 28, 2014 in the journal Neuron, and is linked to higher thinking processes. "We tend to think that being able to plan for the future, being flexible in approach and learning from others are things that are particularly impressive about humans," said Matthew Rushworth, experimental psychologist at Oxford University.

Trace organs are those in some organisms that are small in size and usually without function, but in other organisms they are larger and have definitive function. The evolutionary importance of these vestigial organs is an indication of a common ancestry. A well-known example of a vestigial organ in man is the vermiform appendix, a small, functionless structure that starts from the caecum (structure located at the point where the small intestine attaches to the large).