Dataset: Nucella canaliculata Morphology and Drill Hole Data

Sets of Nucella canaliculata egg capsules were collected from May to June of 2019 from the six study sites. Each set was assumed to contain dogwhelks that were full or half siblings, and considered a "family". Each set of egg capsules was placed in individual plastic tea-strainers with mesh sides and held in flowing seawater at Bodega Marine Laboratory. When dogwhelks hatched, 80 individuals from each family were transferred to a new tea strainer that was then placed in a 1-liter (L) container on a sea table with flowing seawater. Dogwhelks were fed ad libitum a diet of small blue mussel, Mytilus trossulus, that were regularly collected from Bob Creek, Oregon. When dogwhelks reached a size of 5 millimeters (mm) they were moved to a 1-L container to provide more room for growth.

Adult dogwhelks (10 dogwhelks x 8 families x 6 sites = 480 individuals) were scored on their ability to drill M. californianus by giving them mussels of progressively larger size during a 25-week experiment. Mussel size classes offered were: 20mm (+/-5mm), 40 (+/-5mm), 60 (+/-10mm), 90 (+/-10mm), 120 (+/-10mm), 150 (+/-10mm), 170 (+/-10mm). If a dogwhelk drilled a complete drill hole in a mussel of one size class, it then received mussels of the next size class. For mussels ranging from 20 to 120mm, each snail received two mussels, one slightly less and one slightly more than the mean for that size class. For the 150 and 170mm size classes, each dogwhelk only received one mussel. Mussels ranging from 20 to 150mm were collected from Bodega Marine Reserve. If a dogwhelk drilled a 150mm mussel from Bodega Marine Reserve, it then was given a 150mm mussel from Strawberry Hill, Oregon, and then a 170mm mussel from Strawberry Hill. Preliminary research had shown that mussels from Strawberry Hill were thicker than those from Bodega Marine Reserve. Containers were checked regularly to assess if dogwhelks had drilled: the first 2 checks were 2 weeks apart, the next 3 checks were 3 weeks apart, and the final 3 checks were 4 weeks apart. When a mussel was drilled or partially drilled, its length was measured. All drilled and partially drilled mussels were kept for further analyses. All dogwhelks were sexed and their lengths were measured prior to the start and at the end of the experiment to quantify growth.

The largest several mussels drilled or partially drilled for each dogwhelk were used to determine the maximum drill hole depth for each dogwhelk. Mussels were cut on a bandsaw through the drill holes or partial drill hole. Mussel cross sections were scanned (model: CanoScan LiDE 110) and photographs were used to determine the depth of each drill hole using imaging software (ImageJ; Java 1.80_172). Dogwhelks that did not drill any mussels during the course of the laboratory trial were assigned a maximum depth of 0mm.