Within the huge animal kingdom we have a great division between vertebrate animals and invertebrate animals, which differ from each other in their structure.
The definition of invertebrate animals is any animal that does not have a backbone or bones as such, having the body without a defined bone structure as such, which vertebrate animals do have.
Invertebrate animals are believed to be the least evolved type of animal in the entire kingdom, since it is thought that the next link in evolution was the appearance of a bone structure, necessary to be able to walk and better protect the body.
Animals that do not have a backbone usually have a smaller size than vertebrate animals, since without the existence of a backbone they cannot develop an enormous size as some vertebrate animals manage to have.
Being a large group, we have many subtypes of this type of animal, which have great variations among themselves both in habitat and in physiognomy and size that is why this type of animal must be studied in depth.
We are going to explain in depth what invertebrate animals are, explaining in detail the animals of this type and their characteristics.
What do you need:
- Ability to observe your surroundings.
Instructions
- Invertebrate animals without body protection: First and foremost, we are going to explain what the most basic types of invertebrate animals of all are like, that is, those that have nothing to protect their bodies, having their bodies completely naked before the world without any kind of protection from the outside world. Of course, this type is divided into several subtypes.
- The peripheral: They are the most primitive type of invertebrate of all and one of the least known. Within the peripheral we could highlight first of all the sea sponge, which has an asymmetrical body and lives in the ocean.
- The worms: We turn to the second most primitive type of invertebrate animal of all that, as it could not be otherwise, are the worms. The worms are divided into three more subtypes, among which we highlight the annelids (earth worms divided into rings), the nematodes (they are not divided into rings, from here we can highlight some parasites) and the Flatworms (worms with a fairly flat body, highlighting the tapeworm as the best known).
- The coelenterates: The most evolved unprotected invertebrate of all is the coelenterate, which is distinguished by having tentacles and a larger body than in the previous cases. As best examples we could highlight jellyfish and polyps.
- Invertebrate animals with body protection: Now we are going to move on to the most evolved types of invertebrate animals of all, that is, those that have external body protection that helps them achieve a better relationship with the environment due to the great protection it offers against the environment and against some predators. As usual, invertebrate animals with body protection are further divided into other subtypes.
- Arthropods: Arthropods are characterized by having a kind of exoskeleton that completely covers their body, having good protection against the environment. Within them we have insects (6 legs and antennae), arachnids (8 pairs of legs no antenna), myriads (including centipedes with lots of legs) and crustaceans (4 antennas and variable number of legs).
- Mollusks: Mollusks are characterized by having a naked body but at the same time having a shell that covers them, which can be inside or outside. We have a division into subtypes that begins with the cephalopods (inner shell like the squid), followed by the bivalves (two shells like the mussel) and the gastropods (one shell like the snail).
- Echinoderms: Finally we have the last type of invertebrate animal with protection, that is, the echinoderms. We have as the most famous animals of this type the starfish, which have a symmetrical body with a body protection based on small plates. We can also highlight the sea urchins within this group.
Tips
- More than 90% of the animals are invertebrate animals: A very curious fact is that 95% of the animals of all species are invertebrate animals, being something very curious because they are the least evolved animals but the most numerous. This is based on their reproductive strategy (R Strategy), in which females have millions of children to guarantee the survival of the species (because many also die). If you don’t believe me, just look at the large number of insects in the world, which will undoubtedly help you to verify that this information is totally true.
