الهياكل الخارجية وسائر شعب الحيوانات اللافقارية .. كتاب في سبيل موسوعة علمية

Exoskeletons and other phyla of invertebrate animals.

In talking about the exoskeletons of non-vertebrates
Of the animals, we have taken the phylum of molluscs and its classes, and the phylum of arthropods and its classes, as two passing examples of these structures. We have not stopped at them except to the extent that the picture of these structures and their status of these animals is complete.
We do not need to address all the people on this
The pattern goes down the ladder of animals.

Suffice it to say that in the phylum Sponges, the exoskeletons consist of needle-like pieces of calcium carbonate made by the spongy animal and deposited in the basal layer located under the epidermis, or they are pieces like thorns of Silica holding each other together with a horny substance, which is the sponge material you know in bathrooms, or The spongy animal only makes and deposits this pure spongy material.

It is also sufficient to say that corals make their skeletons, calcareous skeletons, which reproduce and produce for us the well-known coral rocks in the seas.

However, we must not forget that the functions of an animal cannot be performed to perfection unless there is a reasonable amount of solidity in the animal’s body, and that there is no good in a body whose entrails are flowing and collapsing into one another, mixing with one another, and twisting one over the other. If we mentioned that the structure, even the external one, is part of its function, such that the animal’s muscles use it as a support and are attached to it when they contract and when they relax, we mentioned the necessity for this external structure (or if you like, the outer covering or skin) to have some solidity and hardness that prevents it from becoming loose.

In non-vertebrate animals, especially the lower ones, there are animals that do not have a skeleton like the one half. An external structure gives it the required rigidity.

In these animals, we find that this solidity is given to the animal by the hydraulic fluid pressure in its body fluids, which is felt by the animal’s skin or skin, so it seeks.

We see this phenomenon occurring, for example, in some soft worms, where pages of constantly contracting superficial muscles help maintain pressure. They are not the muscles attached to the animal's skin for the purpose of movement.

What we say here applies even to animals with
A single cell is like an amoeba. What preserves their shape so that they do not collapse on top of each other is the hydraulic pressure in their fluids.

However, among these primary animals there are animals that have supporting factors that support them. Some cuticles are glabrous, some are keratinized and made of protein. Some of it contains solid limestone or siliceous pieces that support it.

The methods of intentionality are the same in all animals.
As for the internal structure in vertebrates...
As for the exoskeleton and its like in invertebrates. Hydraulic pressure tightens the structure of the animal, especially the lowly animal. To the last thing we mentioned.

One comprehensive goal, many means to achieve it.
If we consider the great multitude of animals, we say:
Yes, the means are many. But there are two great things: the inner structure and the outer structure.

The inner temple was filled with thousands of thousands of animals.

The outside temple spread among thousands upon thousands of animals.