[Animals] Animales Naturaleza

[Mr.Jhorjan]

 

Link:https://es.wikipedia.org/wiki/Animalia

 

In the scientific classification of living beings, animals (Animalia) or metazoans (Metazoa) constitute a kingdom that brings together a broad group of organisms that are eukaryotic, heterotrophic, multicellular, and tissue (except porifera). They are characterized by their wide capacity for movement, by not having a chloroplast (although there are exceptions, as in the case of Elysia chlorotica) or cell wall, and by their embryonic development; which goes through a blastula phase and determines a fixed body plan (although many species can undergo later metamorphosis like arthropods). Animals form a natural group closely related to fungi (kingdom Fungi). Animalia is one of the five kingdoms of the Eukaryota domain, and the human being belongs to it. The part of biology that studies animals is zoology.

The best-known animal phyla appear in the fossil record during the so-called Cambrian explosion, which occurred in the seas some 542 to 530 million years ago. Animals are divided into several subgroups, some of which are vertebrates: (birds, mammals, amphibians, reptiles, fish) and invertebrates: arthropods (insects, arachnids, myriapods, crustaceans), annelids (worms, leeches), molluscs (bivalves , gastropods, cephalopods), porifera (sponges), cnidarians (jellyfish, polyps, corals), echinoderms (starfish), nematodes (cylindrical worms), flatworms (flatworms), etc.

Characteristics
Mobility is the most striking feature of organisms in this kingdom, but it is not exclusive to the group, which is why certain organisms, the so-called protozoa, which belong to the kingdom Protista, are often designated as animals.

The following diagram shows the characteristics common to all animals:

Cellular organization: Eukaryotic and multicellular.
Nutrition: Heterotrophic by ingestion (at the cellular level, by phagocytosis and pinocytosis), unlike fungi, they are also heterotrophic, but they absorb nutrients after digesting them externally.
Metabolism: Aerobic (mandatorily consume oxygen). However, several species of the Loricifera phylum of marine animals have recently been discovered, which have the particularity of being the first metazoans that up to now have been shown to live in a permanent anaerobic environment, since they do not contain mitochondria, but other organelles. .
Reproduction: All animal species reproduce sexually (some only by parthenogenesis), with gametes of very different sizes (oogamy) and zygotes (diplont cycle). Some of them also can reproduce asexually. They are typically diploid.
Development: By embryo and embryonic leaves. The zygote divides repeatedly by mitosis to form a blastula.
Structure and functions: They have collagen as a structural protein. Highly differentiated cell tissues. No cell wall. Some with chitin. Phagocytosis, in basal forms. Ingestion with subsequent phagocytosis or absorption in derived forms ("more evolved"), with the ability to move, etc.