Green sea turtles, despite their name, can actually display a variety of colors. While green is the most common, their shells and skin can range from yellowish to black in color. The coloration depends on a few key factors.
Typical Green Coloration
Most green sea turtles have shells and skin that are varying shades of green, from very light pastel green to almost black dark green. The green color comes from the fat and carotenoid pigments in their diet of seagrasses and algae.
When green sea turtles are young, their shells tend to be darker black and brown. As the turtles grow, their shells gradually lighten to green. Their skin also lightens from nearly black to green. The greenish color provides camouflage in their seagrass feeding grounds.
| Turtle Age | Shell Color | Skin Color |
|---|---|---|
| Hatchling | Black/brown | Black/brown |
| Juvenile | Dark green | Dark grey-green |
| Adult | Medium to light green | Green |
An adult green sea turtle’s shell is often described as having a tortoiseshell pattern, with streaks and mottling of light and dark greens, yellows, and browns. Their skin can range from light yellow-green to darker mossy green.
Non-Green Coloration
While green is the most common, green sea turtles can display other shell and skin colors besides green. These include:
- Yellowish
- Brown
- Reddish or pinkish
- Grey
- Almost black
A small percentage of green sea turtles have shells that are yellowish or brownish in color instead of green. Their skin may also be paler yellow rather than green.
This non-green coloration is due to dietary differences. Turtles with limited access to the normal green sea turtle diet of seagrasses and algae will have less green-hued carotenoid pigments. Their shells and skin take on a more yellowish-brownish tone.
Other turtles can display reddish or pinkish shell and skin coloration. This is caused by algal growth on the turtle rather than pigmentation. Grey or black coloration results from accumulations of barnacles or other organisms on the turtle’s shell.
| Shell/Skin Color | Percent of Population | Cause |
|---|---|---|
| Green | 90% | Normal diet |
| Yellowish | 5% | Limited normal diet |
| Reddish/pinkish | 2% | Algal growth |
| Grey/black | 3% | Barnacle accumulation |
Hatchling Coloration
Green sea turtle hatchlings emerging from the nest have darker black or brown shells and skin. This provides camouflage against predators as the tiny turtles make their way across the beach to the ocean.
Interestingly, the very first layer of a hatchling’s shell is white. As the hatchling grows in the egg, its shell and skin gradually darken to black or brown before hatching.
Within the first few weeks after entering the ocean, the hatchling shell will begin to lighten and take on a greener tone. Its dark skin will also start to lighten.
Color Changes with Age
As green sea turtles grow from juveniles to adults, their coloration changes. This is a gradual process.
Younger juveniles have darker brownish shells and darker grey-green skin. Older juveniles begin to display lighter green shells with some dark mottling. Their skin lightens as well.
Eventually, the adult shell has lighter green coloration with dark streaks, known as a tortoiseshell pattern. The skin becomes yellowish to mossy green.
This color change provides better camouflage as the turtles shift feeding habits. Dark colors blend into the open ocean. Lighter greens blend into seagrass meadows where adults feed.
| Turtle Age | Shell Color | Skin Color |
|---|---|---|
| Hatchling | Black/brown | Black/brown |
| Early juvenile | Dark brown | Dark grey-green |
| Late juvenile | Light & dark green | Lighter green |
| Adult | Tortoiseshell green | Yellowish to mossy green |
Geographic Variations
There are also some geographic variations in the colors and patterns of green sea turtles. These distinctive differences help identify turtles to their population home ranges.
Green sea turtles found around Hawaii typically have a light yellowish tone rather than green. Their shells are often described as golden in color.
Turtles from the Galapagos Islands have darker black shells and skin with visible streaks of white along their necks and heads. Turtles from Costa Rica’s Pacific coast also have darker coloration.
In the Atlantic Ocean, turtles near Cape Verde and in the Caribbean Sea tend to be lighter greens and yellows. Their patterns include white or pale streaking along with the typical tortoiseshell coloration.
| Location | Shell Color | Skin Coloration |
|---|---|---|
| Hawaii | Golden yellow | Yellowish green |
| Galapagos Islands | Dark green/black | Dark grey-green |
| Costa Rica Pacific | Dark green | Dark green |
| Cape Verde Atlantic | Light green | Yellowish green |
| Caribbean Sea | Light green/yellow | Light green |
Conclusion
In summary, while called green sea turtles, these turtles can display a variety of colorations besides green. The most common is green or yellow-green, caused by their carotenoid-rich diet. But some turtles have yellowish, brown, reddish, grey or nearly black shells and skin.
Hatchlings emerge from nests with dark brown or black coloration that helps camouflage them. As they mature, their shells and skin gradually lighten to shades of green better suited for adult feeding grounds.
Geographic populations show distinctive color patterns, from golden shells in Hawaii to dark coloration in the Galapagos. So while named for their green hue, sea turtles actually display a rainbow of colors.
