Activity 2

Crab ID, Adaptations and Abundance

Complete pages 5 and 6 in the student fieldwork booklet for this section.

Learning Intentions

To learn about the identification and adaptations of crabs.

To learn about the method used to measure crab abundance.

Inquiry Questions

What adaptations do crabs have and how do they increase their ability to survive?

What is the size of the crab population at Bobbin Head?

Crab Study Site

Crab Identification

Crab Images

Crab 1

Crab 2

Crab ID Chart

Crab Observations and Adaptations

Mangrove Giants at Bobbin Head NSW AustraliaYoutube (3.08min)

Crab Abundance Investigation

Background

Counting crab numbers is hard as they move around. An easier way is to count crab holes, assuming that 1 hole = 1 crab.

Rather than count every hole in an area to determine the abundance of crabs (which would take a long time), scientists randomly sample areas and use the results to estimate the population.

For sampling the crab abundance at Bobbin Head we use 1 metre x 1 metre quadrats.

Purpose

To estimate the population size of adult crabs in the mangrove forest at Bobbin Head.

Method:

1. Get four 1m2 quadrats (A,B,C,D).

2. Randomly lay them in the mangrove forest.

3. Count the number of adult crab holes in each quadrat and record in a table. Adult crab holes are the larger ones.

Results

Processing Results

Create a table to record your data.

Find the average population for crabs per m2

Page updated

Report abuse