Question

case study: sea turtles and climate change
background information
for most species of turtles, alligators, and crocodiles, gender is not determined during fertilization (like it is for most other animals). instead, the environmental temperature of the developing eggs determines whether the offspring will be male or female. this is called temperature - dependent sex determination, or tsd.

1. summarize the above information into one sentence:

sea turtles are adapted to live their lives in the ocean, but like all marine reptiles, they must leave the ocean to lay their eggs. the image below summarizes the general reproductive cycle of sea turtles, although some details vary by species.
nesting: usually occurring at night, the female crawls out of the ocean onto the beach, digs a hole, up to 2 feet deep. she then deposits 50 - 150 eggs, covers the nest with sand, and returns to the ocean.
incubating: the sea turtles will take from 40 - 80 days to develop before hatching. during this time, they are at risk from raccoons, crabs, storm surge, and human activity.
hatching: once ready, the hatchlings bust out of their thin shell and crawl up through the sand and out of their nest. usually occurring at night, predators are abundant. the hatchlings follow the light on the horizon to reach the edge of the ocean, and off they swim.
mating: female sea turtles return to the location of their own birth. here, they mate with male sea turtles, and within a few weeks will be ready to nest.
juvenile turtles: individual sea turtles have a low chance of survival to adulthood. less than 1 out of 500 baby turtles survive long enough to reproduce themselves. as they grow into adults, turtles may travel long distances from their birth beaches.

1. where do female sea turtles mate and nest?

1. how many eggs are laid and how long do they incubate for?

1. what threats do the sea turtles face before they are even born?

1. only 1 out of 500 baby turtles are estimated to survive to become mating adults. why do you think this number is so low?

Explanation:

1. For the first question, we extract the key - idea about temperature - dependent sex determination from the given text. For the second, we look at the mating and nesting location information in the reproductive cycle description. For the third, we find the details about egg - laying quantity and incubation period. For the fourth, we identify threats during incubation. For the fifth, we consider various factors in the life - cycle that affect survival.
2. Temperature - dependent sex determination means the environmental temperature of developing eggs in turtles, alligators, and crocodiles determines the offspring's gender.
3. Female sea turtles mate and nest at the location of their own birth, which is on the beach.
4. Females deposit 50 - 150 eggs and the eggs take from 40 - 80 days to hatch.
5. Before they are born, sea turtles are at risk from raccoons, crabs, storm surges, and human activity during the incubation period.
6. The survival rate is low because of numerous predators (such as during hatching when they are exposed at night), natural hazards like storms, and human - related threats throughout their life - cycle.

Answer:

1. For most species of turtles, alligators, and crocodiles, the gender of offspring is determined by the environmental temperature of developing eggs, a process called temperature - dependent sex determination (TSD).
2. At the location of their own birth on the beach.
3. 50 - 150 eggs are laid and they incubate for 40 - 80 days.
4. Raccoons, crabs, storm surges, and human activity.
5. Due to predation (especially during hatching when they are vulnerable at night), natural disasters like storms, and human - induced threats.