0
Nematoda is a phylum of worms, commonly called roundworms. Unlike flatworms, they have a digestive system that is like a tube with openings at both ends.
(nematode) unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic
Wiki User
∙ 12y ago
Wiki User
∙ 14y agothey are little pests that eat plants and bug larva and some of them are omnivores.
Add your answer:
Earn +20 pts
What do they eat exactly?
nematods
How do nematods eat?
Nematodes are tiny little worms (somewhat like earthworms but far smaller). They just crawl around and swallow whatever organic matter they happen to find.
What are Vertebrate how are they classified?
Vertebrates or chordates are classified into 7 classes, which are bony fish, cartilage fish, jawless fish, mammals, amphibians, reptiles, and birds. Bony fish are the most common type of fish and include the most amount of species in the vertebrates class. Cartilage fish are commonly known as rays, scates, and sharks. Jawless fish are very rare and are known to be the ancient fish. Reptiles are categorized into Chelonia-turtles/tortoises, squamata-snakes lizards, crocildilians- crocs, alligators and caimen and some others. Amphibians are urodela- salmanders, newts, anura- frogs and toads, apoda- Caecilians. Mammals are dogs, cats, whales, dolphins, horses...... you probably know this. Birds or aves are pretty simple. Birds are birds!! Animals that are not vertebrates include molluscs, arthropods, cnidarians, poriforans, nematods, platyhelmithes, annelids, and way more. there are more invertebrates than vertebrates.
What are tardigrades?
Tardigrades (Waterbears) are a phylum of invertebrate animals, belonging to the articulata and containing app. 750 species. They are a sister group to arthropoda, though some aspects remind to nematods. Tardigrades are quite small meiofaunal animals, the body length ranges between 0.08 mm and 1.5 mm. They have usually four pair of legs (in some species a reduction occurs) and a nervous system with ventral ganglia and a lobed brain. The body is covered with a cuticle that is shed several times during development . The cuticle is chitinous. There is no metamorphosis, though young tardigrades may look slightly different to adults. Tardigrades are oviparous. Some species are facultative parthenogenic, some may be obligatoric parthenogenetic. The fertilization may be internal or external. Tardigrades occur in quite different, also very extreme - environments, from deep sea to the highest mountains, from the tropic to the arctic and antarctic. All Tardigrades are bound to water (marine or fresh water) for active life. They also live on mossy place. Some groups are able to dry up to a cryptobiosis, thus withstanding extreme dryness, heat, deep temperatures (<30 K!) and radiation. During active life they are vulnerable by radiation, as shown by Josh Middleton.
How many jellyfish are born at once?
Moon jellyfish are not fish: Fish are vertebrates and belong to phylum Chordata, while Moon Jellyfish are invertebrates belonging to phylum Cnidaria. Phylum Cnidaria comprises corals, sea anemones, sea whips, sea pens, hydras, Portuguese man-of-war and sea fan corals, along with Moon jellyfish. The members of phylum Cnidaria are multicellular, diploblastic (having two cell layers) radial symmetric organisms, featuring special microscopic cells called nematocysts or sting cells, which enable them to stun and capture their prey.Moon jellyfish resemble floating mushrooms: Moon Jellyfish appear to be like floating mushrooms with a transparent, milky-white, or light purple, bell-shaped body from which numerous long, thread like arms called tentacles, branch out floating underwater like weeping willow branches. The bell shaped upper body can be as large as 18 inches, thereby giving the animal the appearance of a flying saucer. Hence, Moon jellyfish are also often termed as saucer jelly. The bell portion is further divided into eight parts or canals which further branch and reach the digestive system. The jellyfish has only one opening which serves as the mouth as well as the anus.Moon jellyfish are 95% water: Moon Jellyfish do not possess brain, heart, blood, head, eyes or ears. They are 95% water and are basically a floating mouth and digestive system. They have a complex set of nerves that respond to stimuli, but they cannot think. They do not possess any lungs, gills or any tracheal system, and receive oxygen simply by diffusion through a thin membrane. As they have a large bell shaped body, the surface area available for diffusion is also large.Moon jellyfish have two main stages of life: Two dividions or stages of body plan is seen in the lifetime of a Moon jellyfish. The first type or stage is called the polyp stage and the second is the medusa stage. The first stage of life is characterized by two distinctive features, a mouth which is open upwards and attachment to a substrate or a surface. The medusa stage features the bell shaped body of the jellyfish, with the mouth opening downwards. In this stage, they are no longer attached to the substrate and are free swimming. However, in some Aurelia aurita, species the polyp stage does not exist.Moon jellyfish depend on ocean currents for locomotion: Moon jellyfish in their larval stages make use of cilia for locomotion. The polyps use their gastrovascular cavity as a hydrostatic skeleton and also use few muscle like cells for contraction and extension movements. They creep along the substrate by using the muscle cells. The medusa move differently and use muscle cells called coronal muscle, present in the bell shaped upper body. This coronal muscle enables the animal to pulsate by its contraction movements, thereby causing it to move. These impulses sent to the coronal muscles are nervous in origin and are from the sub-umbrellar nerve net.When the muscle cells contract in a rhythmic fashion, movement by jet propulsion occurs. The jellyfish controls these propulsions with the help of rhopalial centers. This swimming function is carried out, not to move from one place to another, but to keep themselves near the surface of the water. They swim horizontally in such a manner, so that at all times the bell shaped upper part remains near the surface of the water, thereby allowing them to spread their tentacles over a large area to catch maximum prey. Moon jellyfish are carried from place to place solely by the movement of ocean currents.Moon jellyfish possess sting cells: The net of tentacles present in the lower part of the body of jellyfish are studded with scores of poisonous sting cells called cnidocytes or nematocysts, which are capable of injecting poison. The moment the tentacles brush against a prey, the numerous sting cells explode, thereby launching barbed stingers and poison into the prey's body. These sting cells are their defense mechanism and help in protecting themselves from predators. Nematocysts also play an important role in food capture.Moon jellyfish are carnivorous: These invertebrates feed on zooplankton and are carnivorous. They feed primarily on mollusks, rotifers, nematods, diatoms, fish larvae, tunicate larvae, crustaceans, protozoans and several other small planktons. When the tentacles brush against the prey, their sting cells render the prey inactive. The inactive prey is then collected primarily on the surface of the jellyfish where they get entangled in the mucus. Further, by flagellar action, the food is passed through the mouth, along the eight canals inside the jellyfish body. These canals run into the stomach and bring the food to the stomach via the ring canal, where it is broken down by digestive enzymes.Gonads are a distinctive feature of Moon jellyfish: Moon jellyfish contain 4 gonads that are situated at the bottom of the stomach. Moon jellyfish attain sexual maturity mostly in spring and summer and reproduction in them is sexual (distinct male and females). These gonads are characterized by bright coloration which can be clearly seen through the transparent bell body. When a Moon jellyfish is observed from above, the gonads appear like 4 horse shoe shaped parts, thereby becoming a distinguishing feature of these animals. These animals when observed during the months of August or September, show distinct pink arms, due to myriads of larvae developing at the edge of the bell shaped upper body.Moon jellyfish are commonly observed to be washed out on the shores of the Long Beach Island beaches during the summer high tides and winds. By the time they get washed by the currents and land on the beach, their tentacles are ruptured and worn out. The bell portion of the Moon jellyfish cannot sting, and if at all you get stung by the tentacles, there is no need to worry as most of them are harmless (only some are poisonous). The stung area will hurt, but application of some household vinegar or urine has proven to be quite effective in treating the sting.
