Earth worms are animals known to all of us, but they have close relatives who live in the sea with surprising colors. This group is the most numerous and diverse of anélidos. In fact, it is estimated that there are about 30,000 species of them. We are talking about the polychetes, and if you still don’t know them, keep reading this ecology article where we will tell you all about these POLITIES: What are, examples and habitat.
What are polystagetic and their characteristics
Polysthes are vermiform animals similar to worms. They are soft and segmented body invertebrates in fragments called metamers. In fact, his body is divided into three:
- Presigmentary head or region: They have a true and differentiated head with a grouping of sensory organs. His eyes are highly developed compared to other anélidos. They also have antennas, palps, and some also have food appendices.
- Trunk or segmented region.
- Pygidio or postsegmented region: It is not segmented and is equivalent to the tail.
Other characteristics of polystagetics are:
- They usually have Very bright colors: Some may even be iridescent.
- They have Locomotive Appendices called parapodes.
- In each segment it has multiple pelillos called quetas or silks: Hence your name. These are accommodated in beams around parapodes and can have a wide variety of forms.
- Exist of all sizes: Some measure just a millimeter, but others can reach 3 meters. This depends on the species.
- They are animals of very varied habits: So they are very important within marine ecosystems. For example, they help keep the soil in good condition, they are part of the food chain, and can even be bioindicators of environmental disturbances.
If you want to know more about bioindicators: what are, types and examples, do not hesitate to take a look at the following ecology article that we recommend.
CLASSIFICATION OF POLITIES
To understand the polystagers, a classification was created that does not correspond to the group’s own phylogenetics, but which is very useful. Such distinguishes between:
- Wandering polystands: They are free life and live swimming in the water column. They are herbivores or carnivores because they can move to seek food. They have very developed locomotor appendices and have well -developed sensory organs to be able to move in their environment.
- Sedentary polysthes: They remain fixed to the substrate in one place and form tubes in which they are guided. Their locomotor appendices are reduced and some of their quetas are modified in uncinos, structures that help them to hold and move inside the tubes. Its sensory organs are also reduced. His gills are featheous. They are detritivorous and depositivores.
Another classification, which responds to phylogenetic relationships, is as follows:
- Scolecida: With 9 families.
- Palpata: It contains all other families.
POLITISTO HABITAT
Most polystagers live in the sea, but there are a few fresh and brackish water. There are in All types of aquatic areas. They can live in the bentos or seabed, in hard or soft substrates. Some species are plantonic. They can live in all types of water: from clean to very contaminated.
Polyhartic feeding
As we have seen, the polychetes are very varied, so it is expected that their diet is also. There are polychets:
- Carnivores: They have jaws to process their food.
- Herbivores: They also have jaws.
- Detritivores: They consume decomposition matter or organic waste produced by other organisms.
- Filters: They feed on particles suspended in the water, mainly of plankton. The polystagers living inside tubes and that do not move are limited to taking out their food appendices to capture the food and filter it from the water.
- Depositivores: They consume what accumulates on the marine ground.
Two types of food can also be distinguished:
- Selective: They only consume a certain type of food.
- Not selective: They consume all kinds of food without restrictions.
POLICYET REPRODUCTION
The reproduction of polican worms too It is very varied. On the one hand, they can be dioic are separate sexes, or hermaphrodites with both reproductive organs in just organism.
On the other hand, there is also sexual and asexual reproduction, the latter by resorting to geming and fragmentation to create new polychetes. Finally, the life of adults goes A few weeks to several years.
Examples of polystagers
Now that we have already seen what polychetes and their characteristics are, in addition to their type of feeding and classification, we will know some examples of polychetes.
Alveolar tubic polychet (Sabellaria Alveolata)
This polychet is sessile and builds its tube completely From sand and shells that are close to him. It can form reefs in the form of a honeycomb in the Atlantic Ocean and in the Mediterranean Sea. It measures 1 to 4 meters.
Holoturias polychetus (CLAVIGERA GASTROLEPIDIA)
Is white with flattened scales on the back and measures 2.5 to 3 centimeters. It is particular because it is a parasite that is housed inside the sea cucumbers. It is found in the Indo Pacific Ocean.
Pacific duster (Sabellastarrte sanctijosephi)
It measures 8 to 10 centimeters and lives in the Indo Pacific tropics. It can be found on the coasts between coral reefs and dizziness. It is very striking because it has “feathers” around an axis, which are really gills. It is purple with white.
Sea mouse (APHRODITA Aculeata)
He has many quetas around him, so many that he looks like a small hairy animal. These quetas shine with the light by detaching iridescence. He is excavator of marine soils and lives in shallow waters in northern Europe. Under quetas has scales. It measures 10 to 20 centimeters.
If you want to read more articles similar to Polysthes: What are, examples and habitatwe recommend that you enter our biology category.
- Del Pilar, Y., Giméne, M., De la Ossa, M., Sánchez, J. and, Ramos, A. (2014). Practical guide for the identification of polican families. Editorial University Club: Alicante.
- Beatty, R., Beer, A., & Deeming, C. (2010). The book of nature. Great Britain: Dorling Kindersley.
