================================================
KEYWORDS FOR DATASET: Larvae, Metamorphose
================================================

=======================================================
ACCOMPANYING DATA PROVIDED BY:  Dr. Patrick Krug
																																					UCLA, Department of Biology
=======================================================

================================
GENERAL EXPLANATION OF THE STUDY
================================

Sea slugs, which live along the Southern California coast, 
produce thousands of microscopic larvae each year. These 
larvae locate and settle onto a patch of vaucherian seaweed, 
before developing into sea slugs.  The accompanying data file 
is from a pilot study on the ability of sea slug larvae to detect 
this kind of seaweed at different tide heights.  Instead of randomly 
swimming until they find this seaweed (as was previously believed), 
these larvae actually "smell" the seaweed when they are passing 
over it in the water.  They do this, it is believed, by detecting 
chemicals that slowly leach out of the seaweed.  This study 
attempts to support this theory by analyzing the ability of 
larvae to distinguish the smell of this seaweed just as the 
tide is coming in -- when the chemicals are most concentrated -- 
and at high tide -- when the chemicals are more dilute due 
to the rising tide.

This study has been published:
Krug, P.J. and R.K. Zimmer. 2000b.  Larval settlement: chemical markers
for  tracing production, transport, and distribution of a waterborne cue.
Marine Ecology Progress Series, vol. 207: 283-296.

=============================
BRIEF DESCRIPTION OF THE DATA          
=============================

Just before the tide came in, one water sample containing filtered 
sea water was collected away from the patch of seaweed.  This sample 
is the control (it is coded 99).  Once the tide washed in, water 
samples were collected above a patch of vaucherian seaweed every 
five minutes, for a total of thirty minutes.  Each of these samples 
was then divided into six, so that there are six replicates for each 
time point.  There are seven time points (0-30 minutes) so there are 
a total of 42 observations, excluding the control.  The control was 
divided into five replicates.  

Fifteen slug larvae were then injected into each of the replicates, 
and the percentage of larvae that metamorphosed was recorded.  This 
percentage is a function of the ability of the larvae to detect the 
chemicals from the seaweed.

========================
HOW TO USE THE DATA FILE
========================

The data file is space delimited text. The first row contains the list
of variables and each remaining row contains the corresponding data for
a specific time. There are no missing data, however the time for the controls 
is coded "99."  Explanations for all variable abbreviations are given below. 

==============================================================
EXPLANATION OF DATA MEASUREMENT ABBREVIATIONS IN THE DATA FILE
==============================================================

time.........time the sample was collected

percent....percentage of larvae that underwent metamorphosis


================================================
STATISTICAL TESTS AND ANALYSES USED IN THE STUDY
================================================
1) Anova
2) SImple linear regression
3) Test for equal variances