Dataset: Predator-prey interactions of Scyphmedusae

To quantify prey capture and encounters with the feeding structures, we recorded the outcome of each stage of the feeding process. Since medusae are not visual predators and they use a feeding current to encounter their prey, we define an encounter as occurring when a prey item is clearly entrained (being transported) by the feeding current of the medusae. Consequently, we will use the term ‘entrainment’ throughout the rest of the manuscript to denote an encounter. The definition for feeding efficiency has been variously defined by previous authors, so for this study we defined different feeding efficiencies based on 3 sequential steps (see equations below): contact (Eq. 1), capture (Eq. 2), and retention (Eq. 3). For this experiment, we defined contact efficiency as the proportion of entrained prey particles that made contact with the feeding structures of the medusae. Capture efficiency was the proportion of contacted prey that were captured, i.e. stuck to the capture surface. Retention efficiency was the proportion of entrained prey that were ultimately ingested. We did not track prey into the guts and assumed if they remained captured for >30 s that they were eventually ingested.

Eq. 1: Contact efficiency = no. prey contacted/ no. prey entrained × 100
Eq. 2: Capture efficiency = no. prey captured/ no. prey contacted × 100
Eq. 3: Retention efficiency = no. prey captured/ no. prey entrained × 100

Capture maps were generated from the 3D videos. During video analysis, individual prey were tracked in relation to the medusae and the medusa’s reflection to observe points of contact. Points of contact were recorded online maps generated by averaging the size ratios of the medusae using dimensions recorded in ImageJ (64 bit, Java 1.8.0_66).

Experiments were conducted at the Marine Biological Laboratory in Woods Hole during the summer (July-August) of 2016. The medusae were provided by the New England Aquarium. Artemia and copepod prey were cultured onsite at the MBL.