1. Protozoa and Algae: Many species of molluscs, especially those that are filter feeders, consume microscopic organisms such as protozoa and algae. They use their gills or other specialized structures to filter these tiny particles from the water.
2. Plant Matter: Herbivorous molluscs feed on various plant materials. Some, such as limpets and certain species of clams, graze on algae and other organic matter attached to rocks or surfaces. Others, like sea hares, feed on fleshy seaweed and marine plants.
3. Detritus: Some molluscs are detritivores, meaning they feed on dead or decaying organic matter. They play an important role in nutrient recycling within ecosystems by consuming detritus from plants, animals, and other organisms.
4. Microorganisms: Certain molluscs, such as nudibranchs, have specialized feeding behaviors. Some nudibranchs consume microorganisms like bryozoans, hydroids, and small crustaceans. They often have unique adaptations, such as cnidarian-like structures, to capture and feed on these organisms.
5. Scavenging and Predation: Some carnivorous molluscs are scavengers, feeding on decaying animal matter. Others are active predators, hunting and consuming live animals. For instance, certain species of octopus, squid, and cuttlefish are known to hunt fish, crustaceans, and other invertebrates.
6. Filtration: Filter-feeding molluscs use specialized structures, such as gills or filtering organs, to capture suspended particles from the water. They strain organic particles, including phytoplankton, zooplankton, detritus, and even small organisms, from the water column.
7. Parasitism: A small number of molluscs are parasites, meaning they live on or in other organisms and obtain their food from them. An example is the parasitic gastropod Entocolax, which lives inside sea cucumbers and absorbs nutrients from their digestive system.
It's important to note that the diet of molluscs can vary within the same species depending on factors like habitat, availability of food, and developmental stage. Some molluscs may have a specialized diet while others may be more generalist feeders, adapting to different food sources based on their environment.