Feeding ecology of free-living aquatic nematodes

Abstract

ABSTRACT: The buccal cavity structure of free-living aquatic nematodes indicates 4 feeding groups:deposit feeders, epistrate feeders, scavengers and predators. This is in contrast to a previous classificationwhich united omnivores and predators and separated deposit feeders into selective and nonselectivegroups. The new classification shows that the previous view that heavy predator pressureplays a major role in the structuring of meiobenthic communities has been much overemphasized. Mostpredatory species in the previous classification are herein recognized as 'garbage collectors', i.e.species with scavenging feeding habits. The actual feeding behaviour of epistrate-feeding speclesshows that they are able to break open cell membranes of food items in the buccal cavity and suck outthe cell contents (juice feeders), in contrast to deposit-feeding species which swallow the whole fooditem (particulate feeders), indicating different sets of digestive enzymes. Buccal cavity morphologywithin predators indicates 2 feeding types. Trans-epidermal uptake of dissolved organic matter issuggested as an additional food supply for thiobiotic species [mainly deposit feeders), hence indicahngmixotrophy. Size, shape, quality and quantity of food items may to some extent explain coexistence ofcongeners. Nematode mobility and mucus release may attract potential food or keep food sources inoptimal condition, i.e. gardening.