Porifers, also called sponges or sponges, are aquatic invertebrate animals fixed in a substrate. The group's name is due to the presence of pores throughout the body.
The porifers belong to the phylum porifera. They have the most varied shapes, sizes and colors. They have a basic body pattern, in the shape of a vase, tube or barrel.
porifers
Features
Habitat
The habitat of most species is the marine environment, few live in fresh water. Sponges are found fixed to the bottom of the sea, in rocks, shells and sand. They can live alone or in colonies.
body structure
The porifers have walls perforated by pores and, inside, there is a cavity called atrium or spongiocele. At the end opposite the base of your body, there is an opening called kiss.
Externally, they are covered by pinacocytes, found and joined cells. The outer wall of the porifers is called the pinacorderme.
The internal cavity is lined with choanocytes, ovoid cells and with flagella. The movement of flagella allows circulation and represents the sponge's circulatory system.
There are also amoebocytes, free cells present between the layers of pinacocytes and choanocytes.
The skeleton of sponges is internal and composed of calcareous or siliceous spikes. It can also be organic, formed by collagen fibers, called spongins.
Sponges lack nervous system and tissues.
vase-shaped sponges
Breathing and Eating
Porifers are filter animals. They promote a current of water that enters through the pores, passes through the atrium, and leaves through the osculum. When entering, the water supplies oxygen and when leaving, it carries carbon dioxide and waste. So, the breathing, through diffusion gas exchange.
THE food it occurs through food particles suspended in water, such as protozoa and unicellular algae. The absorbed particles are captured by choanocytes, which digest some of the substances. The other part is digested by amebocytes and later distributed to all cells.
Learn more about Invertebrate Animals.
reproduction
The reproduction of porifers can be asexual and sexual:
- budding or gemiparity:occurs in some sponges, which occupy an adequate environment in terms of temperature, oxygen supply and food, grow a lot and can develop lateral shoots.
- gemulation: occurs when some freshwater sponges are subject to water scarcity. In this condition, they generate small pockets, with cells with almost no metabolic activity and protected by a resistant coating. When conditions return to being favorable, a new sponge forms.
- Regeneration: sponges have an enormous capacity for regeneration. When cut into several fragments and placed under favorable conditions, each fragment can give rise to a new individual.
In the mesenchyme (jelly-like portion of its interior) sponges can form reproductive cells.
Sperm are produced from amoebocytes and released into the central cavity. These sperm can enter another sponge through the pores and captured by choanocytes, which help in the fertilization of the egg.
A zygote is then formed, forming a mobile larva, which swims until it settles on a substrate, giving rise to a new sponge.
Types and Classification
There are three types of sponges. Learn about each of them:
- ascon - They are the simplest sponges. They have a shape similar to a hollow cylinder, with an upper opening, the osculum.
- Sicon - Sponges with an intermediate complexity. They present the appearance of a vase fixed to a substrate.
- leucon - It's the most complex way. The atrium is reduced and the body wall features a system of channels and chambers.
As for classification, the phylum Porifera has three classes, according to the characteristics of the spikes and cellular organization.
- Calcareous Class - Group sponges with calcareous spikes. They can be of the ascon, sicon or leucon types;
- Hexactinellide Class - Group of sponges with silica spikes. They can be Sicon or Leucon;
- demospongiae class - Sponges with a spongy skeleton, siliceous or mixed. Leucon type only.
Curiosities
- There are believed to be more than 10,000 species of sponges worldwide;
- Before the creation of synthetic sponges, natural sponges were used in the bath;
- Some types of substances produced by porifers can be used to make antibiotics.
- The survival of sponges depends on the movement of water within them. A sponge 10 cm in height and 1 cm in diameter can move more than 20 liters of water a day.
Learn about another group of aquatic animals, the Cnidarians.
