Describing and Understanding Organisms main content.

Some Clues to Describing and Understanding Organisms

Here are some clues to describing and understanding organisms to help focus your biodiversity research, in these three places:

  • in the classroom (as you form your questions and build hypotheses)
  • in the field (as you observe and collect data),
  • in the "lab" (back at school, as you analyze data, create graphic presentations, and review hypotheses)

(Remember: Some clues can be seen only close-up in the lab, but with practice, you'll see many in the field.) 
After noting a characteristic of the organism, always ask yourself, "Why might it be this way? What might this clue indicate?"

For all organisms, consider microhabitat: 
Does the organism always occur in the same "zone"? 

Consider:

  • temperature
  • moisture level
  • sunlight/shade
  • soil type

Plants 

Distribution:

  • Does it occur in clumps, or is it on its own, far from others of the same species?
  • If in clumps, do they seem randomly distributed, or do you see a pattern?
  • Is it always associated with the same plant species, or do you find it with a variety of other plants?

Growth Form:
How does the plant hold itself up when it doesn't have a skeleton?

  • Is it woody or herbaceous (non-woody)?
  • If it's woody, is there one main trunk (trees), or are there several (shrubs)?
  • Does the plant stand up by itself, sprawl along the ground, or use something else for support (vines)?

Leaf Type: Does the leaf look like:

  • a regular broad-leaf, with a little stem (petiole) and a flat, wide blade?
  • a long strap?
  • a needle or a tiny scale?
  • If the leaf has a petiole and blade, what shape is the blade?

Leaf Arrangement: How are the leaves arranged on a stem?

  • Are there two leaves attached to the same part of the stem (opposite)?
  • Are there more than two leaves attached to the same part of the stem (whorled)?
  • Do the leaves attach to the stem in a zigzag or spiral pattern (alternate)?

Reproduction: How does the plant produce offspring?

  • Do you see flowers on the plant?
  • Where are the male and female parts of the flower?
  • How do you suppose the male parts meet the female parts?
  • Do you see fruits or cones on the plant?
  • If so, can you find the seeds?
  • How do you think seeds get around to new locations?

Plant Defense: How do you suppose plants protect themselves from predators when they can't run away?

  • Does the plant have any spines?
  • Do the leaves look very hairy?
  • Are certain parts of the plant very tough and hard to digest?
  • Does the plant have a distinct smell?
  • Do you see anything eating the plant, or signs that something has been eating it?

Arthropods 

Behavior: Look for clues to how and where it earns its living, for example:

  • Is constantly visiting flowers?
  • Does it run around in the open?
  • Is it found only in the dark, under stones or logs?
  • Does it lie waiting in some kind of trap?

Location: Look for clues to the kind of places it prefers.

  • If on vegetation, is it chewing leaves? Piercing? Sucking?
  • Is it always on the same type of plant?
  • Does it occur in large numbers or on its own?

Occupation: What's it up to? For example:

  • Is it involved with another arthropod?
  • Is it eating? Is it being eaten?
  • Is it just "hanging out"?
  • Is it mating? Is it laying eggs?
  • Is it tending to eggs or larvae?
  • Is it carrying eggs or larvae?
  • Is it fighting? Showing off ("displaying")?

Morphology: How's it built?

  • Mouthparts: How do you think it might feed? Might it suck? Pierce? Bite? Does it have poison fangs?
  • Legs and other appendages: How long are they? How long are legs compared to other appendages? (For example, does it have huge rear legs like a grasshopper? Or a long "stinger" like an ichneumonid wasp?)
  • Eyes: How big are they? How complicated? (For example, does it have huge compound eyes like a dragonfly? Or tiny, simple eyes like many spiders?)