Microarthropods

Arthropods are animals with segmented bodies, joint-legs, and exoskeletons. This diverse group contains insects, crustaceans, arachnids, centipedes and millipedes. Currently, arthropods make up almost 62% of the total known species of organisms (that's more than all the other higher order animals combined), and new species are being discovered every day.

Whether measured by numbers of individuals, mass of living tissue, or species numbers, arthropods are the largest, most diverse, and least understood part of most terrestrial ecosystems. Because of their small size and large variety, they have been enabled to fill practically every niche available in their respective ecosystems. Forest entomologists have traditionally viewed arthropods in terms of their negative effects on the production of timber. Even less attention has been given to the vital roles they play in the sucessful functioning of these ecosystems.

Although arthropods live and feed on nearly every part of the plants in terrestrial ecosystems, these same plants depend on the arthropods for their own survival. Besides pollinating the plants and dispersing their various seeds, arthropods are the major force of decomposition of the dead material into nutrient-stuffed topsoil that plants need to grow.

Microarthropod Lab

In this lab, we went to the ropes course behind the school and collected soil samples. We then placed them in plastic bags, labeling them with our names. Each group put their soil sample into a Berlese Funnel Extractor. How to Make a Berlese Funnel Extractor After that we tried to find microarthropods in the sample by looking at it using a microscope. After that, we classified the microarthropods based on a classification sheet and web images.

Identifying Your Microarthropods
Step A. How many walking legs are present?
a. Zero . . . . . . . . . . . . . . . Go to Step NN
b. 4-6 (2-3 pairs). . . . . . . . . . Go to Step K
c. 8 (4 pairs). . . . . . . . . . . . Go to Step G
d. 10-16 (5-8 pairs). . . . . . . . . Go to Step E
e. 18 (9 pairs) . . . . . . . . . . . Go to Step D
f. 20-24 (10-12 pairs). . . . . . . . Go to Step C
g. 26 or more (more than 13 pairs . . Go to Step B



Step B. How many legs are attached to each body segment?
a. 2 (1 pair) . . . . . . Class Chilopoda (Centipedes)
b. 4 (2 pairs). . . . . . Class Diplopoda (Millipedes)



Step C. Are eyespots visible on each side of the head?
a. Yes . . . . . . Class Chilopoda (immature centipedes)
b. No . . . . . . . . . . . . . . . Class Symphyla



Step D. Are the antennae branched?
a. Yes. . . . . . . . . . . . . . . Class Pauropoda
b. No . . . . . . . Class Chilopoda (immature centipedes)



Step E. Are the legs at the front of the body notably DIFFERENT in
shape and structure from legs at the back of the body?
a. Yes. . . . . . . . . . . . . . . . Go to Step P
b. No . . . . . . . . . . . . . . . . Go to Step F



Step F. Are gill openings present ventrally on the last five body
segments?
a. Yes. . . . Crustacea, Order Isopoda (pillbugs and sowbugs)
b. No . . . . . . . Class Chilopoda (immature centipedes)



Step G. Are the last pair of legs different in structure from
the others?
a. Yes. . . . . . . . . . . . . . . . Go to Step P
b. No . . . . . . . . . . . . . . . . Go to Step H



Step H. Is the body divided into two parts, with a distinct
constriction behind the last pair of legs?
a. Yes. . . . . . . . . . . . . Order Araneae (spiders)
b. No . . . . . . . . . . . . . . . . Go to Step I



Step I. Are the first pair of appendages (pedipalps) enlarged as
pincers?
a. Yes. . . . . . Order Pseudoscorpiones (Pseudoscorpions)
b. No . . . . . . . . . . . . . . . . Go to Step J



Step J. Are the legs more than twice as long as the body?
a. Yes. . . . . . . . . . . Order Opiliones (Harvestmen)
b. No . . . . . . . . . . . Order Acarina (mites and ticks)



Step K. Look for evidence of wings on the thorax.
a. One pair of wings present. . . . . Go to Step FF
b. Two pairs of wings present . . . . Go to Step HH
c. Hardened wing covers present . . . Go to Step EE
d. Short wing pads present. . . . . . Go to Step R
e. No visible evidence of wings . . . Go to Step L



Step L. Are visual organs present on the head?
a. Compound eyes present. . . . . . . Go to Step R
b. Only simple eyes (ocelli). . . . . Go to Step P
c. No compound eyes or ocelli . . . . Go to Step M



Step M. How many segments are present in the antenna?
a. Antennae apparently absent . . . . Go to Step N
b. 4-8 segments . . . . . . . Order Collembola (springtails)
c. More than 8 segments . . . . . . . Go to Step O



Step N. Is the head distinct and the body elongate?
a. Yes. . . . . . . . . . . . . Order Protura (proturans)
b. No . . . . . . . . Order Acarina (larval ticks and mites)



Step O. Is there a pair of filaments or pincers on the end of
the abdomen?
a. Yes. . . . . . . . . . . . . Order Diplura (diplurans)
b. No . . . . . . . . . . . . . Order Isoptera (termites)



Step P. How many abdominal prolegs are present?
a. Zero . . . . . . . . . . . . . . . Go to Step R
b. 2-10 (1-5 pairs) . . . Order Lepidoptera (moth larvae)
c. More than 10 (more than 5 pairs) . Go to Step Q



Step Q. Abdominal prolegs are best described as:
a. Rounded and fleshy . . . . Order Hymenoptera (sawflies)
b. Slender and pointed. . . . Order Mecoptera (scorpionflies)



Step R. How many segments are present in the antennae?
a. Less than 8. . . . . . . . . . . . . . Go to Step S
b. 8 or more. . . . . . . . . . . . . . . Go to Step X



Step S. The mouthparts are best described as:
a. Piercing sucking (slender proboscis) . Go to Step W
b. Mandibulate (2-4 palps visible). . . . Go to Step U
c. Hidden within the head . . . . . . . . Go to Step T



Step T. Which of these structures is present?
a. Forked springing organ (furcula) . . . Order Collembola
b. Collophore near hind legs. . . . . . . Order Collembola
c. Abdomen with six segments. . . . . . . Order Collembola
d. Abdomen with more than six segments. . Order Thysanoptera
e. Spindle-shaped body. . . . . . . . . . Order Thysanoptera



Step U. Are there 1 or 2 small nodes (segments) between thorax
and abdomen?
a. Yes. . . . . . . . . . . . . . Order Hymenoptera (ants)
b. No . . . . . . . . . . . . . . . . . . Go to Step V



Step V. Are the mandibles and maxillae as long as the head and
sickle-shaped; also one pair of stout hooks near the anus?
a. Yes. . . . . . . . . . . . . . . . . Order Neuroptera
b. No . . . . . . . . . . . . . . . . . Order Coleoptera



Step W. Where does the proboscis attach to the head?
a. Near the front . . . . Order Hemiptera - Heteroptera
b. Near the back. . . . . Order Hemiptera - Homoptera



Step X. What structures are present on the end of the abdomen?
a. 2 or 3 long, slender filaments . . . Order Thysanura
b. One pair of heavy pincers. . . . . . Order Dermaptera
c. Short cerci, spines, or bare . . . . Go to Step Y



Step Y. Is the first segment of the thorax significantly narrower
than the head and abdomen -- forming a slender "neck"?
a. Yes. . . . . . . . . . . . . . . . . Go to Step Z
b. No . . . . . . . . . . . . . . . . . Go to Step AA



Step Z. Do the mouthparts face forward or downward from the head?
a. Forward. . . . . . . . . . . . Order Isoptera (termites)
b. Downward . . . . . . . . . . . Order Psocoptera (barklice)



Step AA. Are halteres (knobs or clubs) present on the thorax?
a. Yes. . . . . . . . . . . . . . Order Diptera (flies)
b. No . . . . . . . . . . . . . . . . . Go to Step BB



Step BB. Are there 1 or 2 small nodes (segments) between the thorax
and abdomen?
a. Yes. . . . . . . . . . . . . Order Hymenoptera (ants)
b. No . . . . . . . . . . . . . . . . . Go to Step CC



Step CC. Are the hind legs adapted for jumping?
a. Yes. . . . . . . . . . . . . . . . Order Orthoptera
b. No . . . . . . . . . . . . . . . . . Go to Step DD



Step DD. How long are the antennae?
a. Nearly as long as the body . . Order Dictyoptera (roaches)
b. Less than half body length . . Order Coleoptera



Step EE. Does the abdomen end in a pair of stout pincers?
a. Yes. . . . . . . . . . . . . . Order Dermaptera (earwigs)
b. No . . . . . . . . . . . . . . Order Coleoptera (beetles)



Step FF. Are halteres (knobs or clubs) present on the thorax?
a. Yes. . . . . . . . . . . . . . Order Diptera (flies)
b. No . . . . . . . . . . . . . . . . . Go to Step GG



Step GG. The mouthparts are best described as:
a. Biting/chewing (mandibulate) . . . Order Hymenoptera
b. Piercing/sucking (proboscis) . Order Hemiptera - Homoptera



Step HH. The front wings are best described as:
a. Covered with a fine dusting of scales. Order Lepidoptera
b. Half membranous aand half leathery . . Order Hemiptera
c. Rod-like with a long fring of hairs. . Order Thysanoptera
d. Opaque and leathery in appearance. . . Go to Step JJ
e. Rigid and brittle. . . . . . . . . . . Go to Step EE
f. Entirely membranous. . . . . . . . . . Go to Step LL




Step JJ. The mouthparts are best described as:
a. Piercing/sucking (proboscis) . . . . . Order Hemiptera
b. Biting/chewing (mandibulate) . . . . . Go to Step KK



Step KK. Are the hind legs adapted for jumping?
a. Yes. . . . . . . . . . . . . . . . . . Order Orthoptera
b. No . . . . . . . . . . . . . . . . . . Order Dictyoptera



Step LL. Is the first segment of the thorax significantly narrower
than the head and abdomen -- forming a slender "neck"?
a. Yes. . . . . . . . . . . . . . . . . . Go to Step MM
b. No . . . . . . . . . . . . . . . . . . Order Hymenoptera



Step MM. Do the mouthparts face forward or downward from the head?
a. Forward. . . . . . . . . . . . . . . . Order Isoptera
b. Downward . . . . . . . . . . . . . . . Order Psocoptera



Step NN. Is the body divided into segments?
a. Yes. . . . . . . . . . . . . . . . . . Go to Step PP
b. No . . . . . . . . . . . . . Aschelminthes (roundworms)



Step PP. How many segments are visible on the body?
a. Less than 10 . . . . . . . . . Crustacea or Rotifera
b. 10 to 15 . . . . . . . . . . . . . . . Go to Step QQ
c. More than 15 . . . . . . . . . . . . . Annelid worms



Step QQ. The head and mouthparts are best described as:
a. Head distinct with chewing mouthparts. . . Go to Step RR
b. No obvious head, but mouthparts are visible . Coleoptera
c. No visible head or mouthparts. . . . . . . Go to Step VV



Step RR. Are the last pair of spiracles larger than any others?
a. Yes. . . . . . . . . . . . . . . . Order Diptera (flies)
b. No . . . . . . . . . . . . . . . . . . . Go to Step SS



Step SS. Are the head and mouthparts hard and dark-colored,
contrasting with the appearance of the thorax?
a. Yes. . . . . . . . . . . . . . . . . Order Coleoptera
b. No . . . . . . . . . . . . . . . . . . . Go to Step TT



Step TT. Is the body covered with a dense coat of hair?
a. Yes. . . . . . . . . . . . . . Order Siphonaptera (fleas)
b. No . . . . . . . . . . . . . . Order Hymenoptera



Step VV. Are the last pair of spiracles larger and more obvious
than the others?
a. Yes. . . . . . . . . . . . . . Order Diptera (flies)
b. No . . . . . . . . . . . . . . Order Hymenoptera

Guide taken from http://www.cals.ncsu.edu/course/ent525/soil/kwikey1.html

After that, we put all the data in the class on a data table. We then used an equation to determine the percentage of similarity between groups. We put that data on data tables. After that, we made bar graphs of the number of individuals in a site and another one with the species richness.