Fig 1.
Prey species tested for consumption by corals.
a) Costasiella usagi b) Costasiella cf. kuroshimae c) Elysia cf. japonica d) Elysia pusilla e) Plakobranchus cf. ocellatus f) Plakobranchus cf. papua.
Fig 2.
Predator corals tested for consumption of slugs.
a) Fungia fungites b) Pleuractis paumotensis c) Danafungia scruposa d) Heteropsammia cochlea.
Table 1.
Sampling sites at Koh Tao, Gulf of Thailand, indicating which predator and prey species were sampled from which location and total depth range of sampling.
In-situ trials were conducted at all sites.
Fig 3.
Ingestion of sacoglossan species Elysia cf. japonica by Heteropsammia cochlea (a-c) and Elysia pusilla by Fungia fungites (d–f).
Fig 4.
States of consumption of prey items upon extraction from coral mouth.
a) Consumption score 0 showing minimal signs of tissue degradation b) Consumption score 0.5 indicating partial tissue breakdown and c) Consumption score 1 signifying heavy tissue loss.
Fig 5.
Measurements taken of Fungiid corals Fungia fungites (top left) and Pleuractis paumotensis (top right) for the purpose of assessing rates of prey transport. Mt–Mouth, I–Inner Coral, M–Middle Coral, O–Outer Coral, MD–Maximum Diameter.
Fig 6.
Comparison of mean consumption scores between a) prey sacoglossan species b) prey size classes c) in-situ and ex-situ feeding trials and d) predator corals. Error bars represent standard error and y-axis indicates consumption score from 0 (no visible tissue loss) to 1 (heavy tissue degradation).
Table 2.
On the left, mean duration of ingestion and mean time to rejection per species in minutes and proportion of prey items rejected (including incomplete ingestion) as % of total trials per species.
On the right, pairwise Wilcoxon rank sum p values for comparison between prey species for the consumption scores. Significant results were considered as those with p < 0.05.
Table 3.
Comparison of ingestion duration and time to rejection between three size classes of prey, four species of coral predator and between in-situ and ex-situ feeding trials.
Table 4.
Tests of significance and correlation between numerous variables with relation to consumption score, time to completed ingestion and time to completed rejection.
Significant results were considered as those with p < 0.05 or r values > 0.5 with regards to correlation.
Fig 7.
In-situ observations of natural predation of sea slugs by Heteropsammia cochlea.
a) Partial ingestion of Tubulophilinopsis pilsbryi by H. cochlea b) Heteropsammia cochlea in close proximity to Avrainvillea erecta, hosting multiple Costasiella individuals (circled, partially visible).
Table 5.
Mean rates of transport of prey items to the mouth of different mushroom coral species.
All different prey species were tested upon all predator coral species. Rates shown include both in-situ and ex-situ trials.
Fig 8.
Examples of additional test trials with a) Elysia marginata and Fungia fungites, b) Elysia asbecki with F. fungites, c) Aliculastrum debile with F. fungites and d) Elysia pusilla with Truncatoflabellum sp.