DOI: 10.5061/dryad.c866t1gdd
title: Data from: swimming through sand: using accelerometers to observe the cryptic, pre-emergence life-stage of sea turtle hatchlings

description: Animals that hatch within a subterranean nest, such as turtle hatchlings,
 expend some of their limited energy reserves digging out through sand or
 soil to reach the surface. In sea turtles, this emergence process can take
 the hatchlings 3 – 7 days. However, we have a poor understanding of this
 process as it is difficult to observe what is occurring underground. Here
 we utilize a novel method to characterise digging-out behaviour: affixing
 an accelerometer directly to newly hatched green turtles (Chelonia mydas)
 to record movement until nest emergence. Our data revealed that buried
 hatchlings maintained a head-up orientation, but did not move in the
 expected left and right swaying motion associated with alternating limb
 crawling. Rather, they moved using dorsal-ventral heaving and pitching as
 if swimming vertically through the sand to the surface. Movement activity
 was irregular and brief, interspersed by many short periods of inactivity,
 mostly lasting less than 10 minutes. The first 24-hours of head-up
 activity displayed no diel patterns, but the last 24-hours prior to
 emergence involved more intense movement during nighttime hours compared
 with daytime hours. Thus, our results add valuable new insight, and in
 some cases change previous assumptions, regarding the digging behaviours
 during the egg-to-emergence life stage in sea turtles.
description: # Data from: swimming through sand: using accelerometers to observe the
 cryptic, pre-emergence life-stage of sea turtle hatchlings
 [https://doi.org/10.5061/dryad.c866t1gdd](https://doi.org/10.5061/dryad.c866t1gdd) ## Description of the data and file structure **Dynamic Body Acceleration (DBA) & Results Summary Data** Units of measurement for the data are in acceleration (g) that have been processed into Dynamic body acceleration (See the article’s Methods and Supplementary Information for details on data collection and analysis). These CSV files contain the DBA validation and crawling data represented in** (Fig. 2)** and** (Fig. 3)**. File name suffixes represent the orientation of the accelerometer (CU = accelerometer oriented with carapace pointed upward, HU = accelerometer oriented with head pointed upward).  Within each CSV file: (Time = duration in seconds & DBA_x*,* DBA_y*,* DBA_z = the Dynamic body acceleration values for each individual x, y and z axis respectively). Crawling.csv = Hatchling crawling on sand surface for 60 seconds. CU_Heave.csv = Dynamic Body Acceleration values over time for heaving movements while hatchling is in the carapace-up orientation. CU_Pitch.csv = Dynamic Body Acceleration values over time for pitching movements while hatchling is in the carapace-up orientation. CU_Roll.csv = Dynamic Body Acceleration values over time for rolling movements while hatchling is in the carapace-up orientation. CU_Surge.csv = Dynamic Body Acceleration values over time for surge movements while hatchling is in the carapace-up orientation. CU_Sway.csv = Dynamic Body Acceleration values over time for swaying movements while hatchling is in the carapace-up orientation. CU_Yaw.csv = Dynamic Body Acceleration values over time for yaw movements while hatchling is in the carapace-up orientation. HU_Heave.csv = Dynamic Body Acceleration values over time for heaving movements while hatchling is in the head-up orientation. HU_Pitch.csv = Dynamic Body Acceleration values over time for pitching movements while hatchling is in the head-up orientation. HU_Roll.csv = Dynamic Body Acceleration values over time for rolling movements while hatchling is in the head-up orientation. HU_Surge.csv = Dynamic Body Acceleration values over time for surge movements while hatchling is in the head-up orientation. HU_Yaw.csv = Dynamic Body Acceleration values over time for yaw movements while hatchling is in the head-up orientation. HU_Sway.csv = Dynamic Body Acceleration values over time for swaying movements while hatchling is in the head-up orientation. **Diel Data** This CSV file contains the diel data for 8 nests representing the average VeDBA for the first 24 hours and last 24 hours across each 4-hour time block.  The 'Chunks' represent the following time periods:  Chunk 1 = 12:00 - 16:00 Chunk 2 = 16:00 - 20:00 Chunk 3 = 20:00 - 24:00 Chunk 4 = 00:00 - 04:00 Chunk 5 = 04:00 - 08:00 Chunk 6 = 08:00 - 12:00 **Results Summaries** The results summaries file contains information for the proportion that hatchlings were in a specific orientation based on raw accelerometry values relevant to (Fig. 2F); the average amount of dynamic body acceleration (DBA) in each axis (Fig. 2G); the median and maximum inter-pulse interval values in seconds (IPI) relevant to (Fig. 3C) and the median and maximum duration of activity of hatchlings in seconds (Fig. 3D).\ \ Nest = The nest identification number that the accelerometer hatchling was from. HU_Prop = Proportion in head-up orientation. HD_Prop = Proportion in head-down orientation. RSU_Prop = Proportion in right-side up orientation. RSD_Prop = Proportion in right-side down orientation. CU_Prop = Proportion in carapace-up orientation. CD_Prop = Proportion in carapace-down orientation. DBA_X = Average dynamic body acceleration in the X axis for hatchling within the nest. DBA_Y = Average dynamic body acceleration in the Y axis for hatchling within the nest. DBA_Z = Average dynamic body acceleration in the Z axis for hatchling within the nest (See the article’s Methods for details on how we calculated inter-pulse intervals and activity bouts).