Page 20 - One Million Things: Animal Life - The Incredible Visual Guide

Chiton Turtle

FLUID SKELETON
Shell made of Segmented worms, such as leeches
overlapping and earthworms, have no hard skeleton.
plates Bony layer
Instead, an internal fluid-filled tube, called
of external
a hydrostatic skeleton, provides support.
skeleton
Nautilus Leech

Forelimbs
modified to
form wings
Crow
BIRD
A bird’s skeleton is adapted for
flight, and not just by having wings.
Cutaway
shell Hollow bones reduce the skeleton’s
reveals weight, an enlarged breastbone,
chambers or keel, anchors wing-moving
MOLLUSK SHELLS muscles, and strong hind
Made of calcium carbonate, mollusk limbs aid takeoff
shells vary greatly. The chiton’s flat, and landing.
Keel
jointed shell protects it when
provides
attached to a rock, but also allows an anchor
it to roll into a ball. The nautilus for flight
has a spiral shell with gas-filled muscles
SKELETONS
chambers that help it float.

Most animals have a skeleton—a framework that shapes
bodies, protects internal organs, and provides anchorage for
muscles. Vertebrates have an internal skeleton that is usually
made of bone and consists of a backbone attached to a skull
and two pairs of limbs. Insects, crustaceans, and other
arthropods have a hard external skeleton or exoskeleton.
Worms and some echinoderms have a hydrostatic skeleton,
which consists of a fluid-filled cavity controlled by muscles.

Large claws EXOSKELETON
moved by Badger
strong muscles Crustaceans, arachnids, and insects
have exoskeletons that encase their Crustacean cuticle
(outer layer)
body and limbs. Plates of hard,
reinforced with
light chitin meet at joints calcium carbonate
to provide flexibility.
The exoskeleton cannot
expand, so must be molted
(shed) to allow growth.
Common lobster

Spiny spider crab
A group of bones
Tarantula
called the pelvic
girdle attaches hind
limbs to backbone

18 Dragonfly

(c) 2011 Dorling Kindersley, Inc. All Rights Reserved.

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