Methods for collecting Invertebrates

M.RajAssociate ProfessorDept. of Zoology, Darrang CollegeMethods for collecting Invertebrates

Methods applicable to terrestrial habitats

Flight Interception Trap

Preservative (ethanol or a soap solution)

Bait Traps

Berlese Tullgreen funnel

Method for extracting invertebrates from soil and leaf litter.

insect larvae, nematodes, isopods, slugs, and snails, as well as arachnid

Pitfall traps

Likely invertebrates expected to be trapped include ground-dwelling spiders ground-dwelling beetles oligochaete annelids, slugs, etcPreservativePolypropylene glycol

Chemical extractionA solution of 0.2% formaldehyde is thoroughly applied to the soil of desired area and the invertebrates emerging out collected. e.g. earthworms and larva of many fliesFloatation methodArthropod cuticle can be wetted by various hydrocarbon solvents such as gasoline. A soil or leaf litter sample is placed in a mixture of gasoline and water and shaken. The contents are then allowed to settle. The arthropods will tend to be found in the gasoline layer (which floats above the water) while soil, leaves, etc. will tend to be found in the water layer.

Canopy Fogging

Beat sheet

A typical beat sheet is a square piece of white cotton sheeting with two dowels that form a diagonal cross. The sheet is placed under the branch of interest while the branch is shaken or tapped with a stick.

Methods applicable to aquatic habitats

Plankton nets

Silk, Organdie, Muslin, Teryline, Nylon, synthetic fibresPlanktons cannot swim against current

Cylinder samplers

Cylinders of known size slowly lowered onto water to collect crustaceans and planktons

Water pumps and hoseQuantitative plankton sampling. A pump with a rotary action and fitted with flexible inlet and outlet hose pipes is generally used. The inlet pipe is graduated to show the depth of the vertical descent. A weight is also tied to the inlet hole of the hose which makes the pipe easy to sink and keeps it vertically straight in water. This method has certain disadvantages. As the water flows from all directions into the inlet hole at a particular depth, the microhabitat occupied by the plankton cannot be ascertained.

Kick nets

Rock basket sampling

Grabs and Scoops

Dredging

Dredging is excavation activity carried out under water. A fishing dredge is also known as scallop dredge. Oysters, Crabs, Sea cucumber

Methods common to both terrestrial and aquatic habitats

Hand CollectingThe simplest form of collecting is by hand with small vials or collecting jars. It is advisable to carry different sizes of vials in a small bag. The greatest advantage of this method is that one can sample a very large number of different habitats in a short amount of time.

Floodlights, Flashlights and BlacklightsThis is a novel way to capture nocturnal invertebrates. Nearly half of all invertebrates are active at night. A flashlight or headlamp is used to attract the insects which are collected by hand. Blacklight traps include a variety of trap types, but what they all have in common is the "blacklight" or ultraviolet light (UV) and is used for collecting many insects that are active and flying at night and are attracted to UV light. Most likely invertebrates to be encountered include noctuid moths, wolf spiders, fishing spiders, jumping spiders, miscellaneous unusual beetles, dipterans, and hemipterans.

Yellow pan traps

Aerial Net

Sweep netting

Emergence traps

Aspirators and Vacuum devices