Marine annelids may account for over one-third of bottom-dwelling animal species around coral reefs and in tidal zones. [47] Burrowing species increase the penetration of water and oxygen into the sea-floor sediment, which encourages the growth of populations of aerobic bacteria and small animals alongside their burrows. [51]

The annelids or Annelida (also called "ringed worms"), are a large phylum of segmented worms, with over 17,000 modern species including polychaetes, clitellates, ragworms, earthworms and leeches. They are found in most marine environments from tidal zones to hydrothermal vents, in freshwater, and in moist terrestrial environments.

2024年12月26日 · A major invertebrate phylum of the animal kingdom, the annelids number more than 9,000 species distributed among three classes: the marine worms (Polychaeta), which are divided into free-moving and sedentary, or tube-dwelling, forms; the earthworms (Oligochaeta); and the leeches (Hirudinea).

2024年12月26日 · Annelid - Segmentation, Setae, Metamerism: The body of an annelid is often described as a tube within a tube. The body form of polychaetes varies, depending on whether the polychaete is free-moving, sedentary, or pelagic (ocean-dwelling).

2021年2月15日 · Most marine species are polychaetes (two mostly terrestrial groups are earthworms and leaches). Annelids have bilaterally symmetrical, triploblastic (having three layers of flesh--ectoderm, mesoderm, and endoderm),; they have an internal body cavity with a mouth and anus), invertebrate organisms.

The annelids traditionally include the oligochaetes, which include the earthworms and leeches, the polychaetes, which are a marine group, and two other smaller classes. The phyla Mollusca and Annelida belong to a clade called the Lophotrochozoa , which also includes the phylum Nemertea, or ribbon worms (see: Features of the Animal Kingdom ...

2022年8月24日 · The Phylum Annelida is defined by its morphology as segmented worms. They express closed circulatory systems in the same fundamental manner that Homo sapiens do. Annelids are categorized taxonomically into many classes.

2021年2月23日 · Convergent evolution in both directions has enabled annelids to transition from salt water to freshwater, sea to land via beaches, freshwater to soil, and surface water to subterranean water. A superficially simple worm-like body and a mostly benthic/burrowing lifestyle has facilitated radiation into every conceivable environment, making ...

2020年2月19日 · Only a few species of annelids are commonly known to human beings. These include the delightful Rain, Dew or Earthworms that work so hard to make our soils healthy. The Ragworms and Lugworms, used by marine fishermen and the much smaller Tubifex or Red worms, used by aquarists to feed their fish.

2021年2月23日 · Convergent evolution in both directions has enabled annelids to transition from salt water to freshwater, sea to land via beaches, freshwater to soil, and surface water to subterranean water.