Sea Turtle Fun Facts: Hawksbills Compared to Greens

dictionary
"The Pocket Hawaiian Dictionary", by Mary Pukui, Samuel Elbert & Esther Mookini (1975)
hawksbill vs. green identification
Illustrations by Dawn Witherington

Notice the differences between this green (top & left)
​with #MUI100 "Emma" (bottom & right):

Hawksbills (Eretmochelys imbricata)

  • Known as "honu 'ea" or simply  "'ea" in Hawaiian
  • Listed as "critically endangered" 
  • Has a  prominent hawk-like "bill"
  • 4 pre-frontal scales (between their eyes) 
  • Juveniles' carapace (shells) have serrated edges, which often get worn down when they reach adulthood
  • The carapace scutes on the shell overlap, like shingles
  • 2 claws per flipper
  • Nest exclusively in the Main Hawaiian Islands, in very small numbers (likely only ~100 nesting females in all of Hawai'i).
  • They can start nesting in May, but often a month or so later.
  • Females crawl with an alternating gait, so the tracks they leave in the sand are asymmetrical.
  • They an lay up to 5 nests per season, ~2-3 weeks apart.
  • Clutch size averages ~180 eggs the size of ping pong balls.
  • Incubation (typically ~2 months) and sex determination are temperature-related (the warmer the nest, the faster it incubates and more likely to produce female hatchlings).
  • Once they leave the nest, this begins the "lost years" phase of their lives.  They are not seen again in Hawai'i until they reach the size of a hub cap.
  • They forage on a variety of things including algae, sponges, invertebrates, and fish, which is different than most hawksbills in other parts of the world who are thought to primarily be spongivores.
  • Their carapaces grow to be ~3 feet in length.

Greens (Chelonia mydas)

  • Known as "honu"
  • Listed as "threatened"
  • Has a rounded head
  • ​2 pre-frontal scales
  • Carapaces are sometimes scalloped, but not serrated, and are smooth by adulthood
  • The carapace scutes (plates) grow together, like tiles
  • 1 claw per flipper
  • Nest mostly in the Papahānaumokuākea Marine National Monument (500-800 turtles per year), but some nest in the inhabited Main Hawaiian Islands.
  • They typically start nesting in May.
  • Females crawl by pulling themselves forward with both front flippers evenly, so their tracks are symmetrical.
  • They can lay up to 7 nests per season, ~2 weeks apart.
  • Clutch size averages ~100 eggs the size of golf balls.
  • Incubation (typically ~2 months) and sex determination are temperature-related (the warmer the nest, the faster it incubates and more likely to produce female hatchlings).
  • Once they leave the nest, this begins the "lost years" phase of their lives.  They are not seen again in Hawai'i until they reach the size of a hub cap.
  • Once they reach this phase of their lives, they switch from being omnivores to being primarily vegetarians (although they won't turn down an easy protein-packed meal of sea jellies, squid, octopus, fish, crustaceans, etc.).
  • Their carapaces grow to be ~4 feet in length.

Here's a video that showcases the differences between
hawksbill and green turtle tracks:

Hawksbill and green hatchlings look very different:
They look more similar as juveniles and adults:
green & Rocket Girl
This is Don McLeish's photo of "Rocket Girl" (on the right) swimming with a green.

Here's a video about "Leftie", one of our known hawksbills, and a green sea turtle that happened to swim by.  Notice the differences:

NOAA green turtle brochure (Summer 2017):

NOAA Hawaiian Sea Turtle Coloring Book

See pages 7 &  8 for the hawksbills!
noaa_hawaiianseaturtlecoloringbook.pdf
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File Type: pdf
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