Feeding

• We eat to obtain water, protein, energy from lipids and carbs, and micronutrients
• Sponges use choanocytes to draw water in through pores and out through the osculum i.e. filter feeding
• Filter feeding is the ability to obtain nutrients from particles suspended in water
• Cnidarians are typically carnivorous. They have cnidocytes (stinging cells) used to capture prey. These cells contain stinging capsules, nematocysts, which contain coiled threads. When stimulated, the thread shoots out, puncturing and injecting venom into prey
• Flatworms (Platyhelminthes) may be predators, scavengers, or parasites. They have a mouth and a gastrovascular cavity. Parasitic flatworms have modifications such as suckers to help them attach to their host
• Rotifers draw water into their mouth using a crown of cilia (lophophore) and feed on microorganisms suspended in the water column i.e. suspension feeders
• Ectoprocta and Brachiopoda feed on suspended food particles trapped by their tentacles i.e. suspension feeders
• Many molluscs have a radula and are hence often grazers or browsers. Cephalopods are predators and have both a radula and a beak; some have deadly toxins to paralyse their prey. Bivalves don't have radula and are mostly filter feeders.
• Most Annelida are deposit feeders. They obtain nutrients from particles suspended in soil. Annelida may be filter feeders or have symbiotic bacteria. Some are carnivorous and some are parasitic
• Roundworms (Nematoda) are mostly predatory or parasitic
• Arthropoda have incredible jaws. Some are filter feeders. The mode of feeding may change throughout the lifespan such as the change from substrate feeding to fluid feeding
• Echinodermata have unique tube feet that can grasp prey and be used for walking. Starfish evert their stomach around their prey i.e. predators. Urchins have a complex jaw apparatus for grazing on seaweed. Sea cucumbers have tube feet around their mouth used as feeding tentacles. Feather stars (Crinoidea) are filter / suspension feeders
• Chordates have a range of feeding methods, the most common of which is bulk feeding i.e. eating all of an organism
• Fluid feeders obtain nutrients by consuming other organisms' fluids
• Ram feeders and suction feeders ingest prey via the fluids around it