How many varieties of worms live next to humans today, and each type has its own purpose. Some are harmless, swarming in seaweed and coastal silt. Others are parasitic and invading the body of humans and animals. The former are food for birds and fish, while the latter themselves eat the tissues of living organisms. It depends on the environment and the structure of their body cavity.
Helminthology and nematodology are sciences that study worms and their life processes: from egg laying and the emergence of larvae to the formation of adults. The nematode digestive system is complex and diverse. And today we dwell on this question: is there a body cavity in roundworms, and which one?
Types of worms and the structure of their body cavity
When studying worms, you need to pay attention to other types, so that there is something to compare the class of rounds and to know at least approximately their structure. In the process of clarifying the question of whether there is a body cavity in roundworms, we consider briefly the family of crawlers:
- Flatworms have three cell layers: external (ectoderm), internal (endoderm) and middle (mesoderm). They generally do not have a body cavity as such, and the inner space is filled with parenchyma, due to which food is ingested, digested and exited. There is no digestive system, or it is complex-branched without intestines.
- Annelids have a whole (secondary body cavity), in the epithelial layer of which there are partitions that separate segments. These walls divide the cavity and protect the body from external factors. The digestive system is through with the initial, intermediate and anal intestines.
- Roundworms have a schizocel (primary body cavity). The digestive system is through, without septum, with intestines and anal exit. Most of the worms are propagated by an internal algorithm, and individuals are fertilized in parthenogenesis in an independent way.
All inhabitants have one common affiliation - a skin-muscle bag, which brings them together and reckons with one genus. Having determined whether roundworms have a body cavity, the types and structure of its structure, let us move on to a detailed study of the individuals under consideration and their digestive pattern.
Description of the body cavity of roundworms
Having become acquainted with the flat, circular and oval members of the animal world, we will find out more thoroughly about the insides of the last representatives. The primary body cavity of a round worm is also called a pseudo-target. It does not have its own epithelial layer, and it looks like a through hole between the muscle mass and the general intestine. In this space are all the main organs and systems. Here is the center of vital activity of the organism and the entire existence of the nematode. Body cavity of a round worm performs such necessary functions as:
- support and direction of the form;
- muscle formation;
- development of the rigid layer - cuticles;
- fluid transfer under pressure;
- food accompaniment;
- development of metabolic processes.
We gave a superficial characteristic and were confirmed in the answer whether there is a body cavity in roundworms. Yes primary lithophysis exists, and we will talk more about this further.
About Roundworms in General
Nemathelminthes, or nematodes - this is the name of round worms. Their body is oblong and corpulent, thin and sharp at the ends. Among them stand out:
- abdominal
- rotifers;
- hairs;
- scrapers;
- nematodes.
Most worms belong to parasites, and such individuals inhabit animals and humans. These are not very pleasant cohabitants who urgently need to be destroyed with the help of the capabilities of modern medicine. Of these, the following are known:
- human roundworm;
- trichinella;
- whipworm;
- pinworm;
- hookworm.
Deepening in study, we ask the sources: is there a body cavity in roundworms? Yes, the primary body cavity is - we already understand that so. But what is its role not only in the development of a boneless creature, but also in the entry of this pest into the human body?
Gastrotricha (Gastrotricha), or Gastric
Now we know where roundworms have a primary inner citadel. The body cavity in roundworms of gastrotrichs is slightly expressed, and half of its area is occupied by parenchyma cells. The intestines of the digestive tract pass through three levels:
- front - a massive throat;
- medium - glandular;
- back - anal passage.
Turbellaria (protonephridia and areas of the ciliary epithelium, hermaphroditism and parenchymal areas in the body cavity), as well as features present in nemathelminthes (three intestinal nodes and the primary cavity of the body) are characteristic of the structure of the abdominal worms. The excretion system consists of two protonephridia. Fertilized gastrotricha inland. Individual individuals breed in the form of parthenogenesis.
Rotifers (Rotatoria)
Body cavity in roundworms rotifers are highly structured. In the digestive system of this species are present:
- mouth and throat;
- mastax - a stomach of a chewing design;
- middle intestine;
- posterior short intestine;
- anal passage.
The stomach contains a cuticular anvil - the jaw with two hammers. In the middle intestine are two glands for digestion. Two protonephridia work in the excretion system, the channels of which are connected with the bladder and the anus. Rotifers lay seeds through the oviduct attached to the tail intestine, called the cloaca. For the full development of life, the main species of rotatoria necessarily mix parthenogenetic and sexual generations. Rotifers have great vitality, are able to form cysts for waiting out adverse conditions and resettlement.
Hairy (Nematomorpha)
If you ask yourself if there is a body cavity in round hairworms, you can say with confidence: yes. Although she is a little different and different from her colleagues. In general, they are similar in hypodermis and smooth muscles. But the intestines are almost or completely reformed. Adult worms nematomorpha practically do not eat. There is no excretory system either. Only the nervous system contains a near-pharyngeal ring and a neuro-abdominal trunk adhering to it. But the females of this species breed very intensively, laying more than a million eggs in the water through the hind gut.
Scrapers (Acanthocephala)
But is there a body cavity in round worms of scratches? Immediately I want to note the developed schizocele. This parasite has a powerful structure for suction to the donor organism:
- proboscis with hooks;
- proboscis retractor, or muscular cord;
- cervical branch;
- metasoma - trunk area;
- thick hypodermis;
- longitudinal and ring muscles;
- pseudocuticle.
There is no digestive scheme. A pair of protonephridia also belongs to the excretory organs . The nervous system has two trunks on the sides and the ganglion of the head. The genital area consists of two oviducts and a uterus, a vagina and ducts. The giant crests of macrocanthorhynchus hirudinaceus grow preferably in the intestines of piglets, where they enter with the soil and where they reach their maturity. Some individuals are 25 centimeters long.
Nematodes (Nematoda)
Getting acquainted with the most extensive class - nematodes, we have almost come to the knowledge of whether roundworms have a body cavity? Oh sure. And nematoda not an exception to the rule. They have a pronounced internal system in which there is no mesodermal lining, and it is filled with liquid. The digestive branch is also developed in it:
- oral cavity and pharynx;
- esophagus;
- middle intestine;
- hind gut;
- anal passage.
In excretory secretion there is a hypodermis, consisting of one or two cells, also called glands of the neck. Excretory channels and four phagocytic cells pass in the anterior part of the body. The organs of touch (papillae) and chemical perception (amphids) are poorly developed. In the female reproductive system, there are two oviducts, the same number of ovaries and one pair of queens.
In conclusion about roundworms and not only
As we see, the primary cavity in the family of round creepers is diverse and even similar in some respects to the organs of other inhabitants of the fauna. But worms are worms in order not only to be a food chain, but also to remain pests for animals and people. Keep in mind that these small invertebrates can destroy the body within a few months of being in it. This applies not only to round pests, but also to flat, tape and ring parasites. These are such unexpected but dangerous sticks, such as:
- Flukes - hepatic fasciola (Fasciola hepatica), cat fluke (Opisthorchis felineus), lanceolate fluke (Dicrocoelium lanceatum).
- Tapeworms - tapeworms (Cyclophyllidea), pseudophyllides (Pseudophyllidea).
And here it makes no difference whether the predators have a body cavity or not, all measures must be taken to combat them and the instructions must be strictly followed so as not to become infected with larvae. They enter the human body through water and raw or poorly processed livestock meat. And if something bad happened already, then you should not hesitate: it is important to undergo intensive therapy against the invader. Today, this is done by specialized methods quickly and painlessly.
To summarize the discussion about whether roundworms have a body cavity. Yes or no? Now all doubts disappear by themselves - such a space is necessary. It may differ in some criteria, but it is not so important. All such parasites are arranged almost identically. And we humans need to study such an interesting side of the animal world.