blötdjur

Blötdjur, scientifically known as Mollusca, represent a large phylum of invertebrate animals. This diverse group includes a wide range of creatures, such as snails, slugs, clams, oysters, mussels, octopuses, and squid. They are found in nearly all environments, from the deepest oceans to freshwater habitats and terrestrial ecosystems.

A defining characteristic of many blötdjur is the presence of a soft body, often protected by a shell. This shell is typically secreted by a specialized organ called the mantle. The shell can be external, as seen in snails and bivalves, or internal, as in squid. Some blötdjur, like slugs and octopuses, have lost their shells entirely.

Blötdjur exhibit a variety of feeding strategies. Many are herbivores, scraping algae or consuming plant matter. Others are carnivores, preying on smaller invertebrates or fish, while some are filter feeders, straining food particles from the water. Their respiratory systems also vary; aquatic species often have gills, whereas terrestrial species breathe through a lung-like cavity.

Reproduction in blötdjur is also diverse, with many species being hermaphroditic, possessing both male and female reproductive organs. Others have separate sexes. Development can be direct or involve larval stages. Blötdjur play important ecological roles as consumers, prey, and in some cases, as ecosystem engineers. They are also significant to humans, providing food, pearls, and scientific research subjects.