Crittercam on Green Turtles of the Gulf of California

Southwest Fisheries Science Center researcher, Dr. Jeff Seminoff, worked with the National Geographic Crittercam project using turtle-mounted video and data-logging system (Crittercam; National Geographic Society, USA) to study the underwater behavior and dive patterns of green turtles, at a coastal foraging area in the Gulf of California, Mexico. Between August 1997 and June 2002, units were deployed 36 times on 34 green turtles ranging from 64.1 to 96.7 cm in straight carapace length and 38.6 to 120.5 kg in weight. A total of 89.5 h of video was recorded with corresponding dive data (1065 total dives).

Footage from these turtles has been shown to residents of the Mexican town of Bahia de los Angeles to increase conservation awareness.

Learn more in these two research papers:

Underwater behaviour of green turtles monitored with video-time-depth recorders: what’s missing from dive profiles?

Flipper beat frequency and amplitude changes in diving green turtles, Chelonia mydas

crittercam video 0Crittercam on Gulf of California Green Turtles I:
Sea Pen Consumption

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For years we had found evidence of the consumption of sea pens (a stalked marine animal related to sea anemones) in fecal samples of green turtles who live in the Gulf of California. This video shows the first documentation of the strategy green turtles employ to find and consume these unusual prey items.

Crittercam Video 1Crittercam on Gulf of California Green Turtles II:
Movement Type-1 Dive Black Coral Habitat

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Based on VHF and ultrasonic telemetry data, we suspected that green turtles rested occasionally in offshore areas of the study site in Bahia de los Angeles in the Gulf of California. Until the Crittercam footage was examined, however, researchers had no idea what microhabitats were utilized. We now know that the patchy yellow-polyp black coral fields in the study area are important resting sites for green turtles. Whether the turtles rest among the coral to avoid predators or visit the coral fields because they attract potential food sources is unknown and will be the focus of further investigations.

Crittercam Video 3Crittercam on Gulf of California Green Turtles III:
Stationary Benthic Foraging Gigartina

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Sitting still on the sea floor to consume red algae seems like the most energetically efficient diet intake strategy. However the interaction, or at least association, with other species during foraging is a new insight provided by the Crittercam footage. Note in this video that the turtle expels algae fragments from its mouth as it forages. We don’t see the Cortez Angelfishes (Pomacanthus zonipectus) consuming these fragments, but this may be why they are attracted to this turtle.

Crittercam Video 4Crittercam on Gulf of California Green Turtles IV:
Stationary Bentic Foraging Deep Water Anoxic

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Although perhaps the poorest quality video of the series (due to the extreme depth, 45 meters, and resultant darkness) this is by far the most novel behavior documented by this Crittercam study. This ‘benthic mud sifting’ is a first-ever glimpse at how green turtles may consume foods that are buried in the sea floor. In this never-before seen footage, the turtle is seen eating solitary tube worms (Bispira sp.). 

Crittercam Video 5Crittercam on Gulf of California Green Turtles V:
Surfacing Event

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Many theories have been postulated as to how green turtles migrate around the worlds oceans, the most common of which, and the one with the most data, is that turtles use magnetic orientation to move around. However, in this and other surfacing videos from the Bahia de los Angeles foraging area, it appears that turtles may in fact be using visual cues to navigate within this coastal foraging area. Note the islands in the background. In many of our videos, turtles are seen rotating at the surface until an island comes into view, at which time they dive again in the direction of the last-seen island.

Crittercam video 6Crittercam on Gulf of California Green Turtles VI:
Active Benthic (Seafloor) Foraging on Unidentified Algae

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In most cases green turtles find a food patch and settle in to undertake an extended (7-15 minute) foraging bout. However, turtles may also opportunistically consume foods that are encountered during transit dives along the seafloor – as is seen in this video.  

Crittercam Video 7Crittercam on Gulf of California Green Turtles VII:
Active Midwater Foraging Sargassum Part 1 of 2

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Midwater foraging has been suspected for a variety of sea turtles, but strangely, green turtles have not typically been among those turtles considered to do so. However, this sequence – along with several others – during the study indicates that this mid-water foraging may be much more prevalent than previously suspected. Here the turtle is eating the brown alga, Sargassum sp., as it moves from its release point to offshore waters within the study area.

Crittercam Video 8Crittercam on Gulf of California Green Turtles VIII:
Active Midwater Foraging Sargassum Part 2 of 2

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A continuation of the previous video in the series, here we see just how important a turtle’s flippers can be for manipulating food during foraging. Again, a novel behavior for our study and one that is not well known among larger turtles (hatchling turtles do, however, use flippers in similar ways when foraging).

Crittercam Video 9Crittercam on Gulf of California Green Turtles VIIII:
Movement Type-1 Dive Boulder Field Habitat

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“Boulder field crusing” is perhaps the best, although not most scientific way to describe this sequence. Whether this turtle is searching for a resting site or food is not known, but the footage gives a great ‘turtles-eye’ perspective of the typical boulder fields present around most of the islands in the Gulf of California.

Last modified: 2/4/2015