Platyhelminthes

Phylum Platyhelminthes is in the Kingdom Animalia (animals). This covers all phyla except Nemertea flatworms, which is one of the first class of the Platyhelminthes, which have been separated.

The characteristics
Dosoventral flattened body and not segmented. Generally, the class of flatworms live in rivers, lakes, seas, or as parasites in the body of another organism. This group of worms are very sensitive to light. Some examples of planaria that Platyhelminthes are often found under rocks (2-3 cm long), Bipalium who live behind the damp moss (length 60 cm), Clonorchis sinensis, liver flukes, and tapeworms.

Body Structure and Function
Platyhelminthes is a worm that is rated Triploblastik aselomata because it has three layers consisting of embryonal ectoderm, endoderma, and mesoderma. However, this does not have worms mesoderma specialization so that the cells remained uniform and do not form a special cell.

Digestive System
Digestive system of flatworms called gastrovaskuler system, where the circulation of blood but the food through the intestines. Digestive system of flatworms starts from the mouth, pharynx, and continued into the esophagus. On the back of the throat that the intestines have branches throughout the body. Thus, in addition to digesting food, the gut is also distributing food to the entire body.

In addition, the flatworms are also disposing of leftover food by mouth because it has no anus. Flatworms do not have transport systems for the food distributed through the system gastrovaskuler. Meanwhile, O2 and CO2 gas expelled from the body through a process of diffusion.

Nervous System
There are several kinds of the flatworm nervous system:

- Rope ladder nervous system is the simplest nervous system. On that system, central nervous system called brain ganglion is at the head and numbered pair. Of both brain ganglion nerve cords are out of the side that extends in the left and right sides of the body associated with the transverse nerve fibers.
- In the flatworm higher level, the nervous system may be composed of nerve cells (neurons) are differentiated into sensory nerve cell (the cell carrier of sensory signals to the brain), the motor nerve cells (cells from the brain to the effector carrier), and cell association (intermediaries).

Sense

Several types of flatworms have a oseli sensing system, the eye spots that contain light-sensitive pigment. Spots a pair of eyes are usually numbered and located on the anterior (head). The whole flatworms have senses touch and kemoresptor cells throughout the body. Some species also have additional senses aurikula (ear), statosista (pegatur balance), and reoreseptor (organ to determine the direction of flow of the river). Generally, the flatworm has a system called protonefridia osmoregulation. The system consists of berpembeluh channel that ends in flame cells. Its discharge hole called protonefridiofor numbering pair or more. Meanwhile, the rest of metabolism is issued by diffusion through the cell wall.

Reproduction

Flatworms can reproduce asexually by splitting and sexually by cross-breeding, although animals are classified as hermaphrodites.

Classification

Platyhelminthes can be divided into three classes: Turbellaria (shakes feather worms), trematodes (worms suction), Monogenea, and Cestoda (tapeworms).

- Class Turbellaria flatworms that uses a vibrating feathers as a means of motion, for example, is planaria.
- Class trematode has a suction device which is equipped with hooks to attach themselves to the host because this group live as parasites in humans and animals. Some examples of trematode is Fasciola (liver flukes), Clonorchis, and Schistosoma
- Class Cestoda have a chitin-coated skin so it is not contaminated by host enzymes in the intestine. This worm is a parasite in animals, for example, is Taenia solium and T. The species saginata using skoleks to attach to the host's intestine. Taenia reproduce using fertilized eggs and larvae contained in it called onkosfer

Flatworm Life Cycle

Fasciola hepatica
Eggs (with feces) -> ciliated larva (mirasidium) -> water snails (lymnea auricular or lymnea javanica) -> sporosista -> redia -> cercariae -> out of the body of a snail -> stick to the grass / water plants -> form a cyst (metaserkaria) -> eaten lamb (hepatica) / cow (gigantica) -> colon -> liver -> to adults

Chlornosis sinensis
Eggs (with feces) -> mirasidium -> water snails -> sporosista -> produce redia -> produce cercariae -> out of the body of a snail -> freshwater fish (attached to the muscle) -> form a cyst (metaserkaria) -> fish eaten -> digestive tract -> liver -> to adults

Schistosoma javanicum
Eggs (with feces) -> mirasidium -> water snails -> sporosista -> produce redia -> produce cercariae -> out of the body of a snail -> penetrate human skin -> veins

Taenia saginata / Taenia solium
Proglotid (with feces) -> contaminate pig food -> pig -> pig intestine (eggs hatched so hexacan) -> blood -> muscle / meat (sistiserkus) -> human -> human intestine (sistiserkus breaks -> stuck skolex intestinal wall) -> to adulthood in humans -> out with feces

Diseases caused Platyhelminthes
Several species of Platyhelminthes can cause disease in humans and animals. One of them is the genus Schistosoma which can cause schistosomiasis, a parasitic disease transmitted by freshwater snails in humans. When the worms develop in the human body, can damage tissues and organs such as bladder, ureter, liver, spleen, and human kidney. The damage caused perkembanganbiakan Schistosoma worms in the body causing immune reactions. This disease is a disease endemic in Indonesia. Another example is Clonorchis sinensis causing heart worm infection in humans and other mammals. This species can suck human blood. In animals, the flatworm infections can also be found, for example, that attacks Scutariella didactyla Trogocaris shrimp species by sucking the body fluids shrimp.