How do polychaetes eat

The largest nuchal organs are found in the Amphinomidae and the Euphrosinidae, where the ciliated folds on the caruncle represent the nuchal organs; in many other families nuchal organs are not easily seen. Based on our sampling of these environments in southern Australia, polychaete worms often represent about half of all species of macrobenthic invertebrates. Nearly half of all specimens sorted from samples washed over the 0.

Polychaetes exhibit a wide range of feeding strategies, ranging from those which are carnivores, deposit feeders, suspension feeders, herbivores, and opportunistic species. De Kluijve, M. Marine Species Identification Portal : Abyssoninoe hibernica. Woodin, S. Gary T. Banta,Marianne Holmer, Mikael H. Jensen,Erik Kristensen , October 1 Effects of two polychaete worms, Nereis diversicolor and Arenicola marina, on aerobic and anaerobic decomposition in a sandy marine sediment. Chesapeake Bay Life Benthos Polychaetes.

Search for:. Phragmatopoma californica can serve as a metaphor to encourage humans to re-imagine the way we construct our cities. Frank B. Whitfield, Mellissa Drew, Fay Helidoniotis, Food Che, 47, Pei-Yuan Qian. Larval settlement of polychaetes. Hydrobiologia Russell J. Stewart, James C. Weaver, Daniel E. Morse and J. Herbert Waite. The tube cement of Phragmatopoma californica: a solid foam.

The Journal of Experimental Biology. Crustacea, Bryozoa. Diatoms were identified to species or genus. Identifications of food items were made with help from appropriate literature [ 10 , 49 , 53 ] and taxonomic expertise. Trophic group classification was made following the standards set by Fauchald and Jumars [ 22 ]. Jumars et al. Their review and additional literature was checked to classify species feeding guild e. We compared our results from gut contents with the updated guilds proposed by Jumars et al.

Stomach Repletion Index RI was estimated by the visual percentage of gut fullness under a stereomicroscope. Four repletion classes were estimated:.

The percentage of empty guts was calculated individually for each species. Additionally, we calculated a rate of food items per individual of each species, defined as the total number of times an item was recorded regardless of abundance divided by the number of individuals with non-empty guts for each species. Diet breadth was calculated using Levins Index [ 30 ], which is based on the sum of the frequencies of each food item that was found for a given species:.

The index was standardized for values reaching from 0 lowest breadth to 1 highest breadth following the equation [ 26 ]:. Breadth measures can indicate the width of food items that compose the diet of a given species. The similarity of diet composition among species and feeding guilds was assessed by non-metric dimensional scaling NMDS.

Bray—Curtis distance was applied to the matrix of frequency of food items found for each species. The contribution of diatom species to polychaete feeding was evaluated by the mean number of food items and diatoms consumed per filled guts. It is important to note that not every filled gut contained food item, as sand was sometimes the only content found. Thus, the mean number can reach values lower than 1 if sand is the only gut content found for most individuals of a species.

Diatom species were separated in benthic and planktonic to evaluate which form contributed most to polychaete diet and to check for differences on diatom consumption among the contrasting feeding strategies. Feeding guild classification revealed five carnivores, five subsurface deposit feeders, four surface deposit feeders although two also facultative suspension feeders and four omnivores.

Six species were exclusively found at Barra Velha beach, five of those being subsurface deposit feeders, with the exception of C. Most occurred jointly at the two areas, with the exception of E.

Three species had only empty guts H. Aside from those, the lowest percentages of filled guts were found for Capitella spp. The highest percentages of filled guts were found for L. Sand was registered in almost all non-empty guts. Some species had a low variety of food items, especially subsurface deposit feeders, such as Capitella spp. Benthic diatoms were frequently found in the guts of O. Those species were also the ones with the highest variety of food items registered.

Diatom species such as Surirella fastuosa , Navicula sp. Aside from diatoms, other food items were also frequently registered. Foraminifera were consumed by half of the species, and were a frequent item found in guts of S. Radiolaria also occurred in many species, but was especially frequent in O.

Macrophyte detritus i. Macrophyte was remarkably found in three of the four non-empty guts of E. Food items that were rarely registered are mainly related to animal remains. Pteropoda was only found although frequent in guts of D. Eggs were also identified in the guts of D. Some diatom species were also rarely found, but this may be due to local availability rather than selectivity. The mean number of items registered per non-empty gut shows that most species had values lower than 1.

Aside from species which had no food items, the lowest ratios were found for N. In contrast, species such as O. Diet breadth values were generally low. The higher values were registered for O. Most species with lower breadth values were subsurface deposit feeders, such as Capitella spp. Exception to this pattern was the interface-feeder S.

This is likely due to the dominance of one food content Foraminifera in the dissected guts of this species. This dominance reflected on similarity analysis.

Surface-deposit feeding species had similar diet compositions, with the exception of S. The other feeding guilds did not show a strong similar diet composition among its species, especially for macrophagous guilds Fig.

Levins Standardized Index Ba indicating the diet breadth obtained for polychaete species. Species coded according to Table 1. Similarity of diet composition among species and feeding guilds. Diatoms were found in the guts of most species.

Twenty-three diatom species were benthic, whereas 14 were planktonic. From the benthic species, 17 species were pennate and 6 were centric.

The opposite was found for the planktonic forms, where most species were centric diatoms. Benthic forms were more frequently consumed than planktonic.

Surface deposit feeder species had overall higher numbers and rates of diatom consumption, both for benthic and planktonic forms. However, the standard deviation values for the group were very high, due to the low diatom consumption by S.

Subsurface deposit feeders had average values of diatoms registered, with a higher number of items, but a lower rate than omnivores. However, consumption of planktonic diatoms by subsurface species was very low. Omnivores, especially D. Carnivores overall had the lower values of diatom consumption and only benthic forms were registered Table 3.

Results from stomach contents showed a high number of food items consumed by polychaetes. Individual species diet breadths were generally low. Surface deposit feeders, such as O.

Surface deposit feeding species were the main consumers of diatoms, especially benthic forms. Benthic diatoms were generally much more frequently consumed than planktonic forms by all feeding guilds. Few species S. Lack of food items within guts is a common finding in polychaetes [ 16 , 33 ].

This is compatible with carnivory [ 16 , 22 ], as these species usually have smaller guts than deposit-feeders [ 44 ] and the high-quality protein food reduces the need for constant feeding, in comparison to detritus feeding. The finding for these species is compatible with literature [ 15 ], and is especially important for S. Our findings for S. However, some species usually classified as carnivores presented guts with macrophyte and macroalgae fragments E.

In laboratory conditions, E. This result reinforces the assumption that every carnivore polychaete, lacking prey or carrion, may act as a herbivore and this omnivory potential should be considered when guild classification is concerned [ 46 ]. Nonetheless, the lack of gut content in some species explains the overall low breadth values and frequency of diatoms found for the carnivore guild.

In contrast, surface deposit feeders overall had the highest diet breadth values and rate of food items, enabling a more in depth evaluation of their diets. Ampharetid species are usually considered as surface deposit feeders.

No other feeding evaluation was found for the genus Isolda in literature, but our results suggest that the species feed extensively on benthic diatoms. Macrophyte detritus and macrophagous items such as foraminifera, radiolaria and ciliophora were less frequent but also found. These results indicate that diatoms are an important food item to I. Further studies with other Isolda species may help elucidate whether this feature is common for the genus.

Owenia fusiformis had the highest breadth, and highest mean number of items recorded among the species evaluated. This species feeds using a tentacular crown, and is considered an interface feeder, due to the capacity of shifting its habit between surface and suspension feeding depending on the flow intensity [ 39 ]. This dual habit favors the ingestion of both suspended and deposited material, likely resulting in the higher number of records and breadth.

Caution is needed, however, as evidence suggests that O.