TAXONOMY:
-The latin name “geographica” = map, and refers to the lines on the carapace which looks the lines on a map
-The northern map turtle was formerly referred to as the common map turtle,
—BUT was later changed because the adjective “common” was misinterpreted as abundant
FEATURES:
-The northern map turtle is a medium-sized freshwater turtle
-Side of head has a yellow spot behind the eye
-The carapace of both sexes is brown with yellow lines
—but the patterns on the back fades as the turtle ages
-The plastron (the ventral part of the turtle) is mostly bright yellow -Here you see the Northern Map Turtle at the top, with the yellow plastron
-On the bottom row you see its closest relative, the snapping turtle, with the undersized plastron—which prevents it from withdrawing into its shell
-A cool fact is Tas actually took these photos herself! She worked closely with these species, and will talk to you more about that later.
DIET:
-The northern map turtle is a specialist predator
-Diet composed of mollusks and insects larvae (sometimes aquatic invertebrates)
-Males and females northern map turtles differ in diet
-This graph shows the diet composition of northern map turtles from lake Opinicon, Ontario.
--MALES: consume more insect larvae and fewer zebra mussels than females
--FEMALES: consume more mollusks than males (bigger size=can ingest larger snails and mussels)
-Zebra mussels are not native to North America, and are highly invasive.
-They have become a part of the Northern map turtle’s diet
-It is suggested that zebra mussel act as contaminants in aquatic food webs;
—consumption could increase the transfer of contaminants (i.e., mercury).
SEXUAL DIMORPHISM
-The northern map turtle is a strong example of sexual size dimorphism
-Adult females measure up to 265 mm long, while males only measure up to 130 mm
-This graph shows the size distributions of males and females from Lake Opinicon, Ontario.
—Arrows indicate the sizes at sexual maturity.
-Despite the size overlap, males and females can be distinguished:
--MALES have relatively longer tails, and a more oblong carapace
--FEMALES (immature females, overlapping in size with the males) have a rounder carapace and
