Sea Turtle Hatchlings Research Articles

Do swimming loggerhead sea turtles(Caretta carettaL.) use light cues for offshore orientation?

Sea turtle hatchlings emerge from underground nests on oceanic beaches, crawl to the ocean and swim out to sea. The primary cue used to find the ocean from the nest is the brighter oceanic horizon. We conducted laboratory tests to determine if similar visual cues also guide hatchlings while they swim away from land. The stimuli employed were shapes (horizontal bars, circles) and artificial “horizons”;. Responses elicited by these stimuli while turtles crawled and swam within an orientation tank were compared. All hatchlings, whether crawling or swimming, oriented toward shapes. Crawling turtles oriented toward a brighter horizon but swimming turtles did not, even though they could detect it. We conclude that responses evoked by shapes were due to “light trapping”; effects. Responses by swimming hatchlings to more natural horizons suggest that these cues are no longer attractive. Thus it is unlikely that such photic stimuli are of primary importance in guiding hatchling movements offshore.

Orientation by hatchling loggerhead sea turtles Caretta caretta L. in a wave tank

Within minutes after emerging from underground nests, sea turtle hatchlings Caretta caretta L. locate and crawl to the ocean, enter the surf, then maintain oriented courses that lead them out to sea even after they no longer detect land. The cues hatchlings use, while the subject of some speculation, were unknown. Recent field studies show that hatchlings orient toward surface waves. Our experiments, conducted in a wave tank, demonstrate that loggerhead sea turtle hatchlings maintain headings toward oncoming waves. The response does not depend upon visual cues as it persists in the absence of visible light.

An Assessment of Two Methods of Sexing Hatchling Sea Turtles

An Assessment of Two Methods of Sexing Hatchling Sea Turtles

Thermal Relations of Some Australian Skinks (Sauria: Scincidae)

STONEBURNER, D. L. 1982. Satellite telemetry of loggerhead sea turtle movement in the Georgia Bight. Copeia 1982:400-408. , J. I. RICHARDSON AND G. K. WILLIAMSON. 1982. Observations on the movement of hatchling sea turtles. Copeia 1982:963-965. ITH, W. G. 1968. A neo ate A lantic loggerhead rtle Caretta caretta captured at sea. Copeia 1968: ZuG, G. R. 1971. Buoyancy, locomotion, morphology of the pelvic girdle and hindlimb, and systematics of cryptodiran turtles. Misc. Publ. Univ. Mich. 142:1-90.

A Simplified Method for Determining Sex in Hatchling Sea Turtles

A Simplified Method for Determining Sex in Hatchling Sea Turtles

Observations on the movement of hatchling sea turtles

Observations on the movement of hatchling sea turtles

Observations on the Movement of Hatchling Sea Turtles

Observations on the Movement of Hatchling Sea Turtles

Sex ratio bias in hatchling sea turtles from artificially incubated eggs

Artificial incubation of eggs of green sea turtles, Chelonia mydas, above ground in styrofoam boxes results in a 23% drop in the number of hatchlings with ovaries, compared with samples from clutches left on the beach in natural conditions. This masculinization is consistent with the well-known effects of temperature on sexual differentiation in chelonians and with measurements showing that the styrofoam boxes were 1–1·5°C cooler than the sand on the beach at the depth of turtle nests. These findings verify previous suspicions about the use of styrofoam boxes in management programmes for sea turtles, and have implications for the conservation and husbandry of reptiles in general.

AMINO‐ACIDS ESSENTIAL FOR THE GROWTH OF YOUNG GREEN SEA TURTLES (Chelonia mydas)

ABSTRACTThe development of a completely defined amino acid test diet suitable for hatchling sea turtles is briefly discussed. The results of a series of experiments designed to determine the nutritionally essential amino acids required by the hatchling green sea turtle, Chelonia mydas, are presented. Of the 18 amino acids of nutritional significance, nine are shown to be clearly essential, eight are shown to be clearly non‐essential, and one amino acid is shown to be possibly semi‐essential. Possible relationships of the reported results to the protein and amino acid requirements of turtle age classes other than hatchlings are mentioned. Directions of future research and implications for the development of commercial turtle feeds are suggested.

The influence of the sun's position and elevated cues on the orientation of hatchling sea turtles

1. 1. Hatchling sea turtles, Chelonia mydas and Eretmochelys imbricata, reacted to the position of the sun during tests of seafinding ability by deviating from the shortest route to the water. 2. 2. Cutting off cues from close to the horizon disrupted orientation. Introduction of artificial cues elevated above the normal horizon into an otherwise uniform visual situation re-established orientation. 3. 3. The results suggest that any kind of visual stimulus has some effect on the seafinding orientation of hatchling turtles and that this orientation depends on a relatively uncomplicated type of tropotactic reaction.

Nocturnal emergence of hatchling sea turtles: control by thermal inhibition of activity.

HATCHLING sea turtles usually emerge from their nests at night. The hatchlings are buried in the sand and so they cannot use light as a cue. Hendrickson1 has suggested that during the day heat inhibits activity and keeps the turtles below the surface until the cool of night. Previous work has supported this idea in a general way: green sea turtles, Chelonia mydas, tested 2–3 days after emergence, gave sharp decreases in the type of photic activity involved in the journey from the nest to the sea as the ambient temperature was increased over the 21–26° C range2. But to show that in nature temperatures actually limit the emergence of hatchlings to night-time it is necessary to relate the level above which activity declines to the temperatures prevailing by day on the nesting beaches. Furthermore, in order to check that activity tests made in controlled experimental conditions reflect activity in the natural situation, information on the temperatures of nests from which turtles are in the process of emerging is desirable. Accordingly, three new sets of measurements were made.