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Arthropods (continued)


Digestion

Several arthropods are carnivores, but there are also herbivores, which feed on different parts of plants.

The digestive system of arthropods is complete, and food waste, ie feces, is eliminated by the anus.

Circulation

The circulation of arthropods is open, that is, the "blood" circulates not only within the vessels, but bathes spaces in the animal's body. This "blood" is colorless or slightly bluish and does not carry gases, only nutrients.

Breath

In the various classes of arthropods, the type of breathing varies.

Many arthropods are terrestrial, such as insects, diplopods, and kilopods, and they breathe by drawing oxygen from the environment through structures called trachea.

The trachea is linked to muscle fibers that contract and stimulate air to enter the tracheal spiracles.

Aquatic arthropods, such as crustaceans, may have gill breathing. At gills They are structures that draw oxygen dissolved in water for animal respiration. They are present in most aquatic invertebrates and in fish. Microcrustaceans (very small crustaceans) do skin breathing, that is, they breathe through the skin.

Reproduction

In most arthropods, sex is separated and fertilization is internal, that is, the male throws the male gametes into the female's body.

O development can be straightforward: Puppies are already born similar to their parents, as is the case with many arachnids, so these animals do not undergo metamorphosis.

At the indirect developmentAs with most insects, the hatching animal undergoes a metamorphosis before reaching adulthood.

THE metamorphosis may be complete or incomplete. In complete metamorphosis, the animal goes through the larva, pupa and adult phases - this occurs, for example, in butterflies and flies. In incomplete metamorphosis, there is no larval or pupal phase - this is the case, for example, with cockroaches and locusts.