Arachnids | Arachnida

Arachnida is a class of invertebrates with jointed-legs, most have eight legs, but some have front legs that have converted to a sensory function or appendages that appear to be legs. The legs serve various purposes, such as feeding, defense, and perceiving the Arachnida’s surroundings. Almost all arachnids are terrestrial, although some live in freshwater and marine environments. Spiders are the largest order in the class, but mites, ticks, and scorpions are also members of this class. The term, Arachnida, comes from Greek mythology when a prideful human weaver named Arachne was turned into a spider.

How many legs do arachnids have?

Arachnids have 8 legs, 2 main body segments, no wings or antennae, and are not able to chew. In some species arachnids can grow extra appendages that can look like extra legs. They often get confused with insects, but insects only have 6 legs.

What do arachnids eat?

Most species of arachnids can only eat food in a liquid form and not in solids. They do so by squirting digestive chemicals into their prey and then sucking out the body juices. Arachnids typically eat insects and other invertebrates. Mites are the only arachnids who consume a wider variety of food like fungus, plants, dead animals, bacteria, and other invertebrates.

How are arachnids different from insects?

Arachnids have 8 legs while insects have 6. Arachnid bodies are divided into 2 parts, the cephalothorax and abdomen and insect bodies are divided into 3, the head, thorax, and abdomen. Arachnids do not have an antennae nor wings, while all insects have antennae and some also have wings. Insects belong to the Insect class and arachnids to the Arachnida class.

Arachnids Guides
Browse through our curated Arachnids Guides for additional categorizations, tips, details, variations, styles, and histories of Arachnids. Guides provide additional insights into the unique properties and shared relationships between elements.
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.55”-.67” | 1.4-1.7 cm
.51”-.63” | 1.3-1.6 cm
3.1”-3.9” | 7.9-9.9 cm
.02-.17 oz | .5-5 g
3-8 years
Arabian Fat-Tailed Scorpion
1.700
1.600
9.900
0.005
8.00
900
3D
Arabian Fat-Tailed Scorpion
.16”-.22” | .4-.55 cm
.39”-.51” | 1-1.3 cm
2.56”-3.15” | 6.5-8 cm
2 oz | 57 g
5-7 years
Arizona Bark Scorpion
0.550
1.300
8.000
0.057
7.00
10800
3D
Arizona Bark Scorpion
.14”-.24” | 3.5-6 mm (Male); .18”-.28” | 4.5-7 mm (Female)
.12”-.2” | 3-5 mm (Male); .16”-.24” | 4-6 mm (Female)
.95”-1.54” | 24-39 mm (Male); 1.22”-1.85” | 31-47 mm (Female)
1-2 years
Black House Spider
0.700
0.600
4.700
2.00
41600
3D
Black House Spider
.08”-.2” | 2-5 mm
.98”-2.56” | 25-65 mm
.39”-.91” | 10-23 mm
1-3 years
Bold Jumping Spider
0.500
6.500
2.300
3.00
28000
3D
Bold Jumping Spider
.03”-.04” | .7-1 mm
.04”-.07” | 1.1-1.7 mm
.17”-.24” | 4.2-6.2 mm
3-18 months
Brown Dog Tick
0.100
0.170
0.620
1.50
24000
3D
Brown Dog Tick
.09”-.16” | 2.2-4 mm
.08”-.16” | 2-4 mm
.83”-1.46” | 21-37 mm
2-4 years
Brown Recluse Spider
0.400
0.400
3.700
4.00
139000
3D
Brown Recluse Spider
.12”-.18” | 3-4.5 mm (Male); .28”-.37” | 7-9.5 mm (Female)
.12”-.16” | 3-4 mm (Male); .22”-.3” | 5.5-7.5 mm (Female)
.98”-1.38” | 25-35 mm (Male); 2.05”-2.72” | 52-69 mm (Female)
1-3 years
Brown Widow
0.950
0.750
6.900
3.00
61300
3D
Brown Widow
.43”-.67” | 11-17 mm
.35”-.55” | 9-14 mm
5.51”-8.07” | 14-20.5 cm
1-1.5 years
Camel Spider
1.700
1.400
20.500
1.50
247060
3D
Camel Spider
.013”-.016” | .34-.4 mm
.018-.02” | .45-.5 mm
.055”-.063” | 1.4-1.6 mm
2-3 weeks
Clover Mite
0.040
0.050
0.160
0.06
9400
3D
Clover Mite
.06”-.12” | 1.5-3 mm (Male); .14”-.22” | 3.5-5.5 mm (Female)
.05”-.1” | 1.2-2.5 mm (Male); .12”-2” | 3-5 mm (Female)
.33”-.67” | 8.5-17 mm (Male); .79”-1.3” | 20-33 mm (Female)
1-2 years
Common House Spider
0.550
0.500
3.300
2.00
30000
3D
Common House Spider
.28”-.43” | .7-1.1 cm
.43”-.71” | 1.1-1.8 cm
2.75”-4.33” | 7-11 cm
.035-.09 oz | 1-2.5 g
4-12 years
Deathstalker
1.100
1.800
11.000
0.003
12.00
17200
3D
Deathstalker
Deer Tick
129000
.01”-.024” | .2-.6 mm
.02”-.06” | .5-1.5 mm
.08”-.24” | 2-6 mm
2-3 years
Deer Tick
0.060
0.150
0.600
3.00
129000
3D
Deer Tick
.75”-1.02” | 1.9-2.6 cm
1.02”-1.46” | 2.6-3.7 cm
5.9”-7.9” | 15-20 cm
1-2 oz | 28-57 g
5-8 years
Emperor Scorpion
2.600
3.700
20.000
0.057
8.00
24400
3D
Emperor Scorpion
.07”-.17” | 1.8-4.3 mm
.08”-.18” | 2-4.5 mm
2.64”-6.18” | 6.7-15.7 cm
1 year
European Harvestman
0.430
0.450
15.700
1.00
4250
3D
European Harvestman
.39”-.67” | 1-1.7 cm
.75”-1.25” | 1.9-3.2 cm
3.94”-7.1” | 10-18 cm
.14-.25 oz | 4-7 g
7-10 years (wild); 15-20 years (captivity)
Giant Hairy Scorpion
1.700
3.200
18.000
0.007
20.00
4000
3D
Giant Hairy Scorpion
.35”-.55” | .9-1.4 cm
.47”-.71” | 1.2-1.8 cm
1.57”-2.36” | 4-6 cm (Body)
.035-.07 oz | 1-2 g
4-7 years
Giant Whip Scorpion
1.400
1.800
6.000
0.002
7.00
1800
3D
Giant Whip Scorpion
1.57”-2.24” | 4-5.7 cm
1.57”-2.24” | 4-5.7 cm
8.07”-11.42” | 20.5-29 cm
5-6.2 oz | .14-.18 kg
3-6 years (Male); 10-20 years (Female)
Goliath Birdeater
5.700
5.700
29.000
0.180
20.00
120000
3D
Goliath Birdeater
.12”-.14” | 3-3.5 mm (Male); .13”-.24” | 3.2-6 mm (Female)
.11”-.13” | 2.8-3.3 mm (Male); .12”-.22” | 3-5.5 mm (Female)
1.02”-1.18” | 26-30 mm (Male); 1.1”-2.05” | 28-52 mm (Female)
1 year
Green Lynx Spider
0.600
0.550
5.200
1.00
6950
3D
Green Lynx Spider
.03”-.04” | .8-1.1 mm
.07”-.09” | 1.7-2.3 mm
.22”-.31” | 5.5-8 mm
.66-2 years
Lone Star Tick
0.110
0.230
0.800
2.00
57500
3D
Lone Star Tick
1.8”-2.4” | 4.5-6 cm
5.1”-7.1” | 13-18 cm
11.8”-15.75” | 30-40 cm
2.2-10 lb | 1-4.5 kg
12-20 years
Mangrove Horseshoe Crab
6.000
18.000
40.000
4.500
20.00
230
3D
Mangrove Horseshoe Crab
.055”-.07” | 1.4-1.8 mm
.06”-.08” | 1.5-2 mm
.28”-.35” | 7-9 mm
1 year
Peacock Spider
0.180
0.200
0.900
1.00
43000
3D
Peacock Spider
.11”-.13” | 2.7-3.4 mm (Male); .17”-.22” | 4.2-5.6 mm (Female)
.14”-.19” | 3.6-4.7 mm (Male); .22”-.26” | 5.7-6.7 mm (Female)
1.57”-1.97” | 40-50 mm (Male); 2.48”-3.27” | 63-83 mm (Female)
1-2 years
Rabid Wolf Spider
0.560
0.670
8.300
2.00
13900
3D
Rabid Wolf Spider
.006”-.008” | .15-.2 mm
.008”-.01” | .2-.3 mm
.04”-.05” | 1-1.3 mm
2-4 weeks
Red Spider Mite
0.020
0.030
0.130
0.08
12000
3D
Red Spider Mite
.07”-.09” | 1.8-2.4 mm (Male); .19”-.24” | 4.7-6 mm (Female)
.06”-.09” | 1.6-2.2 mm (Male); .17”-.21” | 4.3-5.4 mm (Female)
.43”-.55” | 11-14 mm (Male); 1.1”-1.34” | 28-34 mm (Female)
1-3 years
Redback Spider
0.600
0.540
3.400
3.00
61300
3D
Redback Spider
.2”-.3” | .5-.75 cm
.28”-.39” | .7-1 cm
1.97”-2.75” | 5-7 cm
2 oz | 57 g
3-8 years
Striped Bark Scorpion
0.750
1.000
7.000
0.057
8.00
3800
3D
Striped Bark Scorpion
.26”-.53” | .65-1.35 cm
.47”-.98” | 1.2-2.5 cm
1”-2” | 2.5-5 cm (Body)
.009-.035 oz | .25-1 g
5-10 years
Tailless Whip Scorpion
1.350
2.500
5.000
0.001
10.00
26100
3D
Tailless Whip Scorpion
.22”-.33” | 5.5-8.3 mm (Male); .17”-.26” | 4.3-6.6 mm (Female)
.18”-.28” | 4.5-7 mm (Male); .14”-.22” | 3.5-5.5 mm (Female)
.94”-1.46” | 24-37 mm (Male); .75”-1.1” | 19-28 mm (Female)
1-2 years
Water Spider | Diving Bell Spider
0.830
0.700
3.700
2.00
28800
3D
Water Spider | Diving Bell Spider
.13”-.17” | 3.2-4.3 mm (Male); .25”-.33” | 6.3-8.4 mm (Female)
.13”-.18” | 3.4-4.5 mm (Male); .26”-.35” | 6.7-9 mm (Female)
.75”-1.02” | 19-26 mm (Male); 1.5”-1.97” | 38-50 mm (Female)
2-3 years
Western Black Widow
0.840
0.900
5.000
3.00
10000
3D
Western Black Widow
.06”-.1” | 1.5-2.6 mm (Male); .22”-.32” | 5.7-8.2 mm (Female)
.1”-.18” | 2.5-4.5 mm (Male); .39”-.55” | 10-14 mm (Female)
.55”-.94” | 14-24 mm (Male); 2”-2.91” | 51-74 mm (Female)
1-2 years
Yellow Garden Spider
0.820
1.400
7.400
2.00
34400
3D
Yellow Garden Spider
.05”-.08” | 1.2-2 mm
.06”-.1” | 1.5-2.5 mm
.2”-.35” | 5-9 mm
1-2 years (wild); 2-3 years (captivity)
Zebra Spider
0.200
0.250
0.900
3.00
10800
3D
Zebra Spider
Lone Star Tick (Amblyomma americanum)
Comparison drawing of the Lone Star Tick compared to other arachnids

Every conversation on fearsome ticks and the Lone Star Tick (Amblyomma americanum) will feature because of its painful bite that can make one develop an alpha-gal meat allergy. This generalist feeder is also called Turkey Tick or Northeastern Water Tick and fits in the family Ixodidae, taking on separate hosts in each stage of its life. They are found in the eastern USA and Mexico and derive its name from the silvery-white star-shaped spot close to the nucleus of the female's dorsal. Adult males may have varying white spots surrounding the edges of their shields and all love to attach to prey by questing.

The Lone Star Tick has an overall length between .22”-.31” (5.5-8 mm). Lone Star Ticks have a body length of .12”-.16” (3-4 mm), body width of .07”-.09” (1.7-2.3 mm), and body height of .03”-.04” (.8-1.1 mm). The typical lifespan of the Lone Star Tick is between .66-2 years.

Set of scaled top and elevation drawings of the Lone Star Tick
Every conversation on fearsome ticks and the Lone Star Tick (Amblyomma americanum) will feature because of its painful bite that can make one develop an alpha-gal meat allergy. This generalist feeder is also called Turkey Tick or Northeastern Water Tick and fits in the family Ixodidae.

The Lone Star Tick has an overall length between .22”-.31” (5.5-8 mm). Lone Star Ticks have a body length of .12”-.16” (3-4 mm), body width of .07”-.09” (1.7-2.3 mm), and body height of .03”-.04” (.8-1.1 mm). The typical lifespan of the Lone Star Tick is between .66-2 years.

Set of scaled top and elevation drawings of the Lone Star Tick
Lone Star Tick (Amblyomma americanum)
Height:
.03”-.04” | .8-1.1 mm
Width:
.07”-.09” | 1.7-2.3 mm
Length:
.22”-.31” | 5.5-8 mm
Depth:
Weight:
Area:

Body Length: .12”-.16” | 3-4 mm

Scientific Name
Amblyomma americanum
Lifespan
.66-2 years

Drawings include:

Lone Star Tick top view, side

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Red Spider Mite (Tetranychus urticae)
Comparison illustration of the size of a Red Spider Mite to other species of arachnids

If you are looking for the smallest, most damaging pest, then the Red Spider Mite (Tetranychus urticae) should be on top of your list. Also called Two-spotted Spider Mite, this plant-feeding pest has origins in Europe but is now a cosmopolitan species that is so small, almost microscopic. It is red or green and spins a fine web beneath the leaves of a wide variety of both wild and cultivated plants. The mite prefers warm and dry places like greenhouses or summer temperatures and is very destructive since it reproduces quickly. It has five development life stages made up of two nymphal stages.

The Red Spider Mite has an overall length between .04”-.05” (1-1.3 mm). Red Spider Mites have a body length of .016”-.02” (.4-.5 mm), body width of .008”-.01” (.2-.3 mm), and body height of .006”-.008” (.15-.2 mm). The typical lifespan of the Red Spider Mite is between 2-4 weeks.

Scaled collection of drawings of Red Spider Mite in various poses
If you are looking for the smallest, most damaging pest, then the Red Spider Mite (Tetranychus urticae) should be on top of your list. Also called Two-spotted Spider Mite, this plant-feeding pest has origins in Europe but is now a cosmopolitan species that is so small, almost microscopic.

The Red Spider Mite has an overall length between .04”-.05” (1-1.3 mm). Red Spider Mites have a body length of .016”-.02” (.4-.5 mm), body width of .008”-.01” (.2-.3 mm), and body height of .006”-.008” (.15-.2 mm). The typical lifespan of the Red Spider Mite is between 2-4 weeks.

Scaled collection of drawings of Red Spider Mite in various poses
Red Spider Mite (Tetranychus urticae)
Height:
.006”-.008” | .15-.2 mm
Width:
.008”-.01” | .2-.3 mm
Length:
.04”-.05” | 1-1.3 mm
Depth:
Weight:
Area:

Body Length: .016”-.02” | .4-.5 mm

Scientific Name
Tetranychus urticae
Lifespan
2-4 weeks

Drawings include:

Red Spider Mite top view, side

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European Harvestman (Phalangium opilio)
Comparison drawing of the European Harvestman compared to other spiders

Its close relatives may be mites and not spiders, hence the European Harvestman (Opiliones) is no true spider. It falls under the class Arachnida and is separated from other long-legged spiders by a single pair of eyes in the cephalothorax middle and fused body regions. This cosmopolitan creature is also called Daddy longlegs, Harvester, or Harvestmen. Since they are not true spiders, they lack silk glands hence can’t build a web or produce venom. Therefore, their defense mechanisms include a suit of armor that may counter chemical secretions from a predator, freezing, fleeing, and bobbing. The European Harvestmen swallow both solid and liquid foods.

The European Harvestman has an overall legspan length between 2.64”-6.18” (6.7-15.7 cm). European Harvestmen have a typical body length of .16”-.35” (4-9 mm), body width of .08”-.18” (2-4.5 mm), and body height of .07”-.17” (1.8-4.3 mm). The common lifespan of the European Harvestman is between 1 year.

Set of scaled top and elevation drawings of the European Harvestman
Its close relatives may be mites and not spiders, hence the European Harvestman (Opiliones) is no true spider. It falls under the class Arachnida and is separated from other long-legged spiders by a single pair of eyes in the cephalothorax middle and fused body regions.

The European Harvestman has an overall legspan length between 2.64”-6.18” (6.7-15.7 cm). European Harvestmen have a typical body length of .16”-.35” (4-9 mm), body width of .08”-.18” (2-4.5 mm), and body height of .07”-.17” (1.8-4.3 mm). The common lifespan of the European Harvestman is between 1 year.

Set of scaled top and elevation drawings of the European Harvestman
European Harvestman (Phalangium opilio)
Height:
.07”-.17” | 1.8-4.3 mm
Width:
.08”-.18” | 2-4.5 mm
Length:
2.64”-6.18” | 6.7-15.7 cm
Depth:
Weight:
Area:

Body Length: .16”-.35” | 4-9 mm

Scientific Name
Phalangium opilio
Lifespan
1 year

Drawings include:

European Harvestman top view, side

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Giant Hairy Scorpion (Hadrurus arizonensis)
Scale illustration of an average Giant Hairy Scorpion compared to other scorpion species

Noted as the largest scorpion found in North America, the Giant Hairy Scorpion (Hadrurus arizonensis) is a species of scorpion found in the Mojave and Sonoran deserts and throughout Arizona as well as parts of California, Nevada, Utah. Within this range, it typically burrows under rocks or seeks shelter between crevices to stay cool. Its common name is derived from the tiny brown hairs along its body and tail which help it to feel the ground’s vibrations in order to catch prey. These sensing hairs along with its large size and aggressive disposition makes hunting for the Giant Hairy Scorpion an easy task.

The Giant Hairy Scorpion has an overall length between 3.94”-7.1” (10-18 cm) and weight of .14-.25 oz (4-7 g). Giant Hairy Scorpions have a body length of 1.93”-3.23” (4.9-8.2 cm), body width of .75”-1.25” (1.9-3.2 cm), and body height of .39”-.67” (1-1.7 cm). The typical lifespan of the Giant Hairy Scorpion is between 7-10 years in the wild and up to 15-20 years in captivity.

Scaled collection of drawings of Giant Hairy Scorpion in various poses
Noted as the largest scorpion found in North America, the Giant Hairy Scorpion (Hadrurus arizonensis) is a species of scorpion found in the Mojave and Sonoran deserts and throughout Arizona as well as parts of California, Nevada, Utah. Within this range, it typically burrows under rocks.

The Giant Hairy Scorpion has an overall length between 3.94”-7.1” (10-18 cm) and weight of .14-.25 oz (4-7 g). Giant Hairy Scorpions have a body length of 1.93”-3.23” (4.9-8.2 cm), body width of .75”-1.25” (1.9-3.2 cm), and body height of .39”-.67” (1-1.7 cm). The typical lifespan of the Giant Hairy Scorpion is between 7-10 years in the wild and up to 15-20 years in captivity.

Scaled collection of drawings of Giant Hairy Scorpion in various poses
Giant Hairy Scorpion (Hadrurus arizonensis)
Height:
.39”-.67” | 1-1.7 cm
Width:
.75”-1.25” | 1.9-3.2 cm
Length:
3.94”-7.1” | 10-18 cm
Depth:
Weight:
.14-.25 oz | 4-7 g
Area:

Body Length: 1.93”-3.23” | 4.9-8.2 cm

Scientific Name
Hadrurus arizonensis
Lifespan
7-10 years (wild); 15-20 years (captivity)

Drawings include:

Giant Hairy Scorpion top view, side

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Water Spider | Diving Bell Spider (Argyroneta aquatica)
Comparison drawing of the Water Spider | Diving Bell Spider compared to other spiders

Spiders prefer ground or arboreal dwellings, however, the Water Spider (Argyroneta aquatica) is different: spending most of its life underwater, only to resurface when replenishing its oxygen supply or to seek prey. Besides, it is the only spider where sexual dimorphism favors males. It resembles a diving bell from where it gets its name. Look for it in freshwater ponds, streams, and other shallow water bodies with abundant vegetation in Europe or Asia. The spider belongs to the family Dictynidae and creates a dome-shaped web where it dwells after filling the web with air. The spider is a night feeder with a bite that is non-venomous.

Male and female Water Spiders (Diving Bell Spiders) vary in size. The female Water Spider has an overall legspan length between .75”-1.1” (19-28 mm), body length of .31”-.47” (8-12 mm), body width of .14”-.22” (3.5-5.5 mm), and body height of .17”-.26” (4.3-6.6 mm). The male Water Spider has an overall legspan length between .94”-1.46” (24-37 mm), body length of .39”-.59” (10-15 mm), body width of .18”-.28” (4.5-7 mm), and body height of .22”-.33” (5.5-8.3 mm). The common lifespan of the Water Spider is between 1-2 years.

Set of scaled top and elevation drawings of the Water Spider | Diving Bell Spider
Spiders prefer ground or arboreal dwellings, however, the Water Spider (Argyroneta aquatica) is different: spending most of its life underwater, only to resurface when replenishing its oxygen supply or to seek prey. Besides, it is the only spider where sexual dimorphism favors males.

Male and female Water Spiders (Diving Bell Spiders) vary in size. The female Water Spider has an overall legspan length between .75”-1.1” (19-28 mm), body length of .31”-.47” (8-12 mm), body width of .14”-.22” (3.5-5.5 mm), and body height of .17”-.26” (4.3-6.6 mm). The male Water Spider has an overall legspan length between .94”-1.46” (24-37 mm), body length of .39”-.59” (10-15 mm), body width of .18”-.28” (4.5-7 mm), and body height of .22”-.33” (5.5-8.3 mm). The common lifespan of the Water Spider is between 1-2 years.

Set of scaled top and elevation drawings of the Water Spider | Diving Bell Spider
Water Spider | Diving Bell Spider (Argyroneta aquatica)
Height:
.22”-.33” | 5.5-8.3 mm (Male); .17”-.26” | 4.3-6.6 mm (Female)
Width:
.18”-.28” | 4.5-7 mm (Male); .14”-.22” | 3.5-5.5 mm (Female)
Length:
.94”-1.46” | 24-37 mm (Male); .75”-1.1” | 19-28 mm (Female)
Depth:
Weight:
Area:

Body Length: .39”-.59” | 10-15 mm (Male); .31”-.47” | 8-12 mm (Female)

Scientific Name
Argyroneta aquatica
Lifespan
1-2 years

Drawings include:

Water Spider (Diving Bell Spider) top view, side

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