CK12 Life Science

Table 12.4: (continued)

Subgroup of Arach-

nid

Representative Or-

ganisms

Approximate Num-

ber of Species

Description

Scorpiones Scorpions 2,000

Characterized by

a tail with

six segments,

the last bear-

ing a pair of

venom glands

and a venom-

injecting barb

Predators of small

arthropods

and insects,

they use pin-

cers to catch

prey, then ei-

ther crush it or

inject it with

a fast-acting

venom, which

is used to kill

or paralyze

the prey; only

a few species

are harmful to

humans

Nocturnal; during

the day find

shelter in holes

or under rocks

Unlike the majority

of arachnids,

scorpions

produce live

young, which

are carried

about on the

mother’s back

until they have

molted at least

once; they

reach an age of

between four

to 25 years

http://www.ck12.org 370