Invertebrate animals are organisms that do not have a spine. They constitute the vast majority of animal species on the planet, covering an incredible diversity of shapes, sizes and habitats. They can be found in virtually every ecosystem, from deep oceans to tropical forests and arid deserts.

These animals encompass groups such as insects, mollusks, arachnids, crustaceans, echinoderms, among others. Despite the absence of spine, many invertebrates have complex and specialized structures that allow them to perform vital functions such as mobility, food, reproduction and defense.

Then know the 9 groups of invertebrate animals!

1. Porifers

Also known as spongurians or simply sponges. They probably emerged about 1 billion years ago. It is supposed to be originated from beings unicellular and heterotrophs that cluster in colonies.

2.

They may present in two forms: polyps or jellyfish. Polyps have a cylindrical body and usually live fixed, for example, on a rock. At their free end, they have tentacles around the mouth. Meduses have the body in the shape that resembles an umbrella. Its tentacles are distributed along the bank of the body, in the center where the mouth is. They swim freely, though usually limitedly, or are charged by the water chains.

3. Platelminths

They are usually flat worms that emerged on earth probably about 600 million years ago. These animals comprise around 15,000 species, live mainly in aquatic environments, such as oceans, rivers and lakes; They are also found in wet terrestrial environments.

Some have free life, others parasitize various animals, especially vertebrates. Measuring from a few millimeters to meters in length, the platelminths have incomplete digestive tube, that is, they have only one opening – the mouth – where they eat food and eliminate feces; Therefore, they have no anus. Some neither digestive tube have and live adapted to parasitic life, absorbing, through the skin, the food previously digested by the host organism.

4. NEMPLIMED

They are worms of cylindrical body, tapered at the ends. Many species are free and live in aquatic or terrestrial environment; Others are parasites of plants and animals, including the human being. There are more than 10,000 species of this type of cataloged worms, but calculations made indicate the existence of many other speciesstill unknown.

Unlike platelminths, nematelminths have a complete digestive tube with mouth and anus. They usually have separate sexes, and the differences between the male and the female can be quite clear, as in the case of the main human parasites. In general, the male is lower than the female of the same age and its posterior end has a hook form. These animals are wrapped in a thin and delicate protective film, very smooth and resistant.

5.

The worm belongs to the phylum of annelids – a name that includes worms with the segmented body, divided into rings. The annelids comprise about 15,000 species, with representatives living in moist soil, freshwater and saltwater. They can be parasites or free life.

The body of annelids is covered by a thin and damp skin. This is an important feature of skin breathing – breathing performed through the skin, as respiratory gases do not cross dry surfaces. They are considered the most complex of worms. In addition to the complete digestive tract, they have a closed circulatory system, that is, they have mouth, anus and a circulatory system where the blood only circulates inside the vessels.

6. Mollusks

They have a fragile composition, they are soft animals, but most of them have a shell that protects the body. In this group we find the snail, the seafood and the oyster. There are also those with the internal and reduced shell, such as Lula, and those who have no shell, such as octopus and slug, among other examples. The snail and slugs are in garden, garden, where there is vegetation and the earth is very wet after a good rain.

Your skin produces viscous secretion, also known as MUCO, which facilitates its locomotion on trees and harsh stones without hurting trees and stones the body. It consists of head, feet and visceral pasta. Visceral mass is inside the shell and comprises the digestive and reproductive systems.

7. Arthropods

Includes animals such as Spider, Fly, Siri, Lacraia, Cobre Louse, Shrimp, Scorpion, Bee, among others. The group of arthropods is so well well to the different environments that it currently represents more than 70% of known animal species. The main feature that differentiates the arthropods from other invertebrates is the articulated paws.

The exoskeleton covers and protects the body of these animals from many external dangers and prevents them from losing water. Among the arthropod classes, we can mention: arachnids, kilopods (lacraia), diplopods (louse), insects and crustaceans.

8. Arachnids

Includes spiders, scorpions and ticks. The body of the arachnids is divided into cephalothorax and abdomen. These animals have four pairs of paws and have no antennas. They have a pair of pedipalpos (palpos), which are sensory appendages, and a pair of chelicerars, tweezers. Most arachnids are carnivorous.

9. Insects

Includes ant, cockroach, mosquito, butterfly, fly, beetle, ladybug, bee, grasshopper, among many others. It is the main class that represents the arthropods. The class with the largest variety and number of species is the only one with wing representatives, which contributes to the success in the occupation of all environments on the planet, except for oceanic waters deeper.

In the head, there is a pair of antennas and a pair of eyes, besides the oral apparatus. The type of oral apparatus relates to the insect feed type and is used by scientists as one of the main classification criteria.

By Tao Consult