Isopods: a Moisture Preference

Abstract:

Porcellio scaber, the sowbug were observed in a plastic container with two mounds of dirt at either end. One mound was moistened with water while the other was left dry. In five three minute trials the number of sowbugs in either environment or in between the two mounds were recorded. The averages were calculated and a one-way ANOVA single factor analysis was done. The data was significant at p=0.03704. There was a difference in the number of sowbugs in each environment. A comparison of the means indicated that the sowbugs were more often found in the moist environment.

Introduction:

The sowbug is small, dark colored terrestrial crustacean that is related to the roly-poly, of the species Armadillidium. Although the sowbug does not roll up as a defense mechanism against attack like its relative isopods, it has specialized glands to deter predators. These isopods typically feast upon decaying plants or animals and are often found hiding under rocks and rotting woods where it is moist. They have pseudotracheae which must remain moist and therefor isopods are more frequently found in wet environments. Therefor it was predicted that if isopods prefer moist environments then there would be more sow bugs found in the wet mound than the dry mound at the end of each three minute trial. Twenty-five sowbugs placed randomly into groups of five were placed into a container and the number of sowbugs in each environment was recorded after three minutes.

Methods:

Sowbug collection: Twenty-five sowbugs of about the same relative sizes were collected  from #KSCAnimBehav provided by Dr. Karen Cangialosi at Keene State College and placed into a tub for holding.

Environment Preparation: A shallow plastic container of 6in X 4in was obtained and two mounds of the same size of the mixed dirt substrate were placed at either end. One of the mounds was moistened with water from a spray bottle.

Trials: Five of the sowbugs from holding were randomly selected and placed into a beaker upside in the plastic container. The beaker was removed and the sowbugs were allowed to roam for three minutes. At three minutes the number of sowbugs in the wet mound, dry mound, or between the mounds was recorded. These five sowbugs were placed into a different holding container to avoid reuse in subsequent trials. This was repeated four more times for a total of five trials that each had new randomly selected sowbugs for observation.

Data Analysis: Averages for each environment were calculated. A Kruskal-Wallis Test was done on the data to determine significance.

Results:

There was a greater average number of isopods that were found in the wet environment as compared to the dry and the between averages.

Figure 1: Mean number of isopods found at each location with standard errors. 

Standard deviations were larger in the between and dry groups suggesting a greater variance for these environments compared to the smaller variation that was calculated for the wet environment. The wet environment had the greatest average of sow bugs found during this experiment. The Kruskal-Wallis test found H=-44.47 which is not significant at p=0.009.

Discussion:

The sowbug is one of few terrestrial crustaceans that must keep their respiratory surfaces moist. It was predicted that more isopods would be found in a moist environment. There were more isopods found in the wet environment in the five trials than in either the dry or between the two mounds. However, the results were not significant at p=0.009 indicating that there is  no moisture preference. In Figure 1, the wet environment has the highest mean and smallest variance whereas the were few to none found in between. The dry environment was frequented by only by 28% of the sowbugs whereas the wet environment had 60% of the sowbugs. It is possible that more scans were needed with more sow bugs to show a preference.

Appendix:

Trial (3min intervals) Number in Wet Number in Dry Between Environments
1 2 3 0
2 2 1 2
3 4 0 1
4 2 3 0
5 5 0 0

Table 1: Number of isopods in the different environments for each of the five 3-minute trials. 


Environment Mean
wet 3
dry 1.4
between 0.6

Table 2: Average number of isopods in the different environments. 


 

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Xenopus laevis: Larvae Ethogram

Amphibians are fascinating creatures due to the metamorphosis that changes the physiology of the larvae to the adult stage. While adult Xenopus laevis have been studied extensively, the behavior of the tadpoles has little information available. These creatures, originally from Africa but with multiple generations bred in the lab, were studied in petri-dishes that contained 10% Holtfrieter’s solution to mimic the pond environment. The tadpoles that were observed on February 1st, 2018 were eleven days old at stage 49(nf) as confirmed by Dr. Whittemore’s lab at Keene State College.

To begin to understand the behavior of these tadpoles, a single larvae was placed into its own petri-dish and observed. After compiling a set of behaviors another tadpole was added and new behaviors and interactions were recorded. A scan sample of the two and a continuous sample on the larger tadpole were conducted for five minutes each to determine how often tadpoles partake in each activity that was observed and described.

**It is important to note that these tadpoles had been used in a neurology course at Keene State College earlier the same day and this stimulation could have impacted the behavior for this observation**

“A tadpole looking back at you.” by H. Schofield (CC 4.0)

Ethogram of Xenopus laevis Tadpoles

Individual Observation: 

Breathing- the head of the tadpole appears to move up and down in a bobbing motion as the mouth opens and closes to force water into the mouth and over the gills to take in oxygen. Is visible when the tadpole remains in one place.

Resting- tadpole remains in one spot, may vibrate tail but does not move, is often seen breathing.

Swimming- tail vibrates, moves back and forth to propel the tadpole forward.

Dancing- as the tadpole swims, the body rocks from side to side, exposing the underside of the organism. Often the tadpole spins and flips itself over in a rolling motion.

Attempted Swimming- continues to move tail from side to side but does not move forward due to an obstruction such as the wall of the container.

Flipping- while swimming the underside turns upright momentarily but does not complete the roll, turn back to normal and continues to move forward throughout the motion.

Vertical Propelling- tadpole moves downward toward the ground and swims in a vertical rather than horizontal/forward movement.

Twisting- while swimming the body rocks and the tadpole swims on its side.

Tail wagging- tail is rapidly moving but the tadpole remains still.

Group Observation:

Mouth Touching- two tadpoles face each other and the front of the head/face touch.

Cuddling- tadpoles congregate and rest together.

Chasing- tadpoles swims after another tadpoles and they bump into one another which changes the direction of the tadpole that is being chased.

Colliding- two tadpoles swim into one another.

Observations

  • Head bobbing was an indication that the tadpole was opening its mouth to pull in water to breathe. There were on average 50 head bobs per 30 seconds in both light and dark environments.
  • In a five minute scan sample with scans at 30 second intervals for a total of ten intervals, the tadpole was resting for 8/10 of the scans, 1 scan saw it swimming, and 1 scan saw it tail wagging.
  • In a five minute continue sampling on the larger tadpole in the petri-dish found that this tadpole spent 49.87% of the five minutes breathing, 45% of the time wagging its tail, 3.44% of the time attempting to swim. and 1.69% of the time colliding into the other tadpole.

Questions

  1. Would there be more collisions if there had been more than 2 being observed?
  2. Would there be more vertical propelling if tadpoles were placed in a container with more depth?

Hypothesis

  1. Tadpoles collide more often when they are in more crowded containers.
  2. Tadpoles experience more vertical swimming when in a container with more depth.

Predictions

  1. If there ten tadpoles in a container together then there would be more collisions per 5 minutes than in a container of the same size that contained only five tadpoles.
  2. If ten tadpoles were placed in a 100 mL beaker then there would be more scans that saw vertical propelling per five minutes than if ten tadpoles were placed in a 50 mL beaker.

 

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Introduction to the Cricket Lab

“Crickets from #kscanimbehav” by H. Schofield (CC by 4.0) 

Animals are always doing something…they rest, sleep, eat, walk, jump, climb, chirp, and so many more. Observing behavior requires patience, a close eye, and the ability to refrain from interpreting behavior. On January 18, 2018, I received about 40 crickets to observe for my animal behavior course. From that moment on a new journey began and although there have been some bad times, there have also been times of beauty and learning. I have been watching and listening to these critters to find out what they do and to investigate reasons behind these behaviors. The story has just begun.

“Cricket home for observational learning opportunities #kscanimbehav” by H. Schofield (CC by 4.0)

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Ethogram: an Observation of Crickets

Cricket Behaviors

States:

For how long did the cricket do this?

Resting- is remaining still, standing on the ground or the top/side of an object.

Walking- is using legs to move self forward across a surface

Hiding- resting in a Dixie-cup house or under objects/dirt.

Events:

How many times/how often does it occur?

Climbing- is actively crawling up an object in the container, often remain on the top or side. Enters into a resting state or climbs down.

Wall Scraping- forelegs rapidly beat against the container wall, hind legs attempt to force the cricket higher.

Eating/Drinking- stands on food/wet towel, uses mouth appendages to scrape food/water droplets towards the mouth for consumption.

Jumping- hind legs launch the cricket up and forward.

Jumping/Walking/Climbing onto another cricket- movement onto another cricket. Sometimes a resting state is started or it continues to move about.

Jumping Away- when poked with a pen or container near it is flicked or jostled it uses the hind legs to launch itself in the opposite direction of the disturbance.

Digging- use of forelegs to move sand away to form a hole.

Carrying- picking up and moving food, dead crickets, or scrap paper to another location.

Grooming- moving antennae and legs through mouth using the palps.

Chirping- noise emitted when the males lift their wings and vibrate the abdomen. Pitch and number of chirps varies. Is more frequent at night and when the container is placed somewhere dark.

Antennae Movements- both antennae move about the air space above the cricket, touch the walls of the container or objects within the container.

Antennae Touching- occurs between two crickets when their antennae touch each other.

Questions:

1. There was an injured cricket that was approached by another, who attempted to drag it away from the wall. Why would a cricket drag another one somewhere else?

2. Do crickets chirp more often when in a warm or cold environment?

Hypothesis:

1. Crickets are detritivores and will eat their dead.

2. Crickets will chirp more often when placed in an environment that is warmer than room temperature.

Predictions:

1. If a cricket were placed in a warm environment above room temperature then it would chirp more times per five minutes than when in an environment that is colder than room temperature.

2. If a cricket were placed in a cage with a dead cricket then it would consume the dead cricket.

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