Arthropod survey. Part one: Aquatic crustaceansPlease examine tagmata and locomotion in three different crustaceans. You

should obtain a picture of each and be able to describe the types, number of appendages and how they and other structures are used in locomotion in each species. Are they using the whole appendages as the “effective” leg or just part of it to move? Your pictures should label antennae and “ effective legs”. Your descriptions should include any tagmata you can see.

All containers should be rinsed with spring water before organisms are placed in them. Be careful to note if you are working with a saltwater or freshwater species. So as not to contaminate cultures please discard your specimen when you are done or place in main tank. If freshwater it will die but will be eaten by a snail or some other detritus feeder.

1. Daphnia Everyone should look at locomotion in Daphnia, the common water flea. a. These are

highly transparent organisms and you can easily compare their anatomy to that of the Caprellid shrimp of last week. If you can obtain a photograph of a Daphnia, label heart as well as antennae. B. Also note: Are any females carrying eggs? Daphnia when crowded becomes pink to red as individuals develop hemoglobin. Can you think of any reasons for this? Is there any evidence that our cultures have individuals that have developed hemoglobin?

c. Obtain a movie of Daphnia movement. d. Your journal should also contain a paragraph on how Daphnia uses its appendages to move. e. Compare the way Daphnia moves to that of the Caprellid shrimp and glass shrimp in your journal.

A reference diagram for Daphnia

Examine the isopods and one of the other aquatic crustaceans available.

2. Freshwater isopod. a. Obtain a photograph and b. label regions and c. describe how appendages are used in locomotion. d. You will compare these fresh water isopods to the terrestrial isopods or pill bugs. As in most crustaceans, the isopod body is divided into three distinct regions: head (= cephalon), thorax (=pereon), and abdomen (= pleon). Please use the more general terms, head, thorax and abdomen for labels on your photograph.

3. You may choose between freshwater crayfish, freshwater amphipods, or freshwater or saltwater copepods as your third crustacean in which to examine locomotion. It would be good if each table choose a different species and then you could compare locomotion in each. All species move rather quickly.

Choices availableFreshwater or saltwater amphipods. a. Obtain a photograph and b. label regions, head, thorax and abdomen and c.

describe how appendages are used in locomotion.

or Freshwater or saltwater Copepod. Cope is greek meaning an “oar” or “paddle;” pod is Greek for “foot.” This should serve as a hint for how these individuals move. You will probably find copepods on most of the marine specimens you will view in the future and so you need to be able to recognize these small animals. a. Obtain a good image of a copepod for your journal. You may have to place a copepod on a slide under the light microscope to obtain a good image. b. Describe how these animals locomote.

We do have marine copepods, which are bigger than freshwater forms, that you can examine. However, do not mix salt water with fresh. Rinse your dishes with several washes of spring water after viewing marine copepods. Marine specimens can tolerate some fluctuations in salinity. Your freshwater specimens however cannot be put in salt water

Or. Freshwater crayfish. We keep a Procambarus sp. first found in Germany. It is an

unusual species in that males are lacking. This variety is know for being

parthenogenetic. Meiosis is suppressed in females, who essentially clone themselves whenever they produce eggs.

Unfortunately, none of our females are carrying eggs. However, if you wish to use one of these for examining locomotion in fresh-water crustacean, feel free to do so. Take good notes, as you mayl not be able to film these species. Those of you with smart phones may want to click a few shots and email the pictures to yourself for your journal.

----------------------- Ostracods We do not have ostracods today, but a diagram of these animals is included because

you may also see a number of marine ostracods on your specimens in the future. An ostracod is a segmented crustacean with head, thorax and abdomen. The head has very hairy legs and usually at least one eye. The rest of the body is very short and ends in a multi-pronged tail (furca). The whole body is enclosed in the carapace, which hinges on the back and is held shut by strong muscles. Sometimes the antennae can be extruded through a notch at the front. Most ostracods are very small, fewer more than 4 mm long but some deep-water pelagic species grow to 30 mm.

4. Sexy shrimp

Before you begin to work with terrestrial forms, check on the sexy shrimp, Thor amboinensis, in the aquarium. These animals sways their abdomens back and forth in a style determined sexy, hence their name. Many functions have been postulated for the swaying, among them territorial defense, mating, etc. You may have used them as a model for locomotion last week. Do you notice any groupings? Are the animals more active in groups?

Before moving on to an examination of terrestrial arthropods, your instructor should with the class compare and contrast the specimens examined. What if you were presented with just one of these species. How would you know if it was a copepod, isopod, etc.?

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Part two.Terrestrial arthropods5. PillbugsExamine the pill bugs or land isopods available. There are several species of varying

size and color that are living happily together in an aquarium. All are US natives.

Compare its morphology to the fresh water amphipod or isopod that you observed. Compare how it uses its legs to walk with how the fresh water amphipod used its limbs to swim?

6. Millipedes

Obtain a millipede. Make sure you record whether you are working with Sigmoria aberrans (black with yellow or pink on edges) or Narceus americana (longer than Sigmoria and uniform in coloration). Count the number of legs found per segment. Observe and record if you can locomotion in the millipede. How much of the body moves as a unit when moving forward? When turning? Transfer your millipede to a sand surface (sand is bumpy and so you will be able to see leg movement better). What type of tracks would left by the moving millipede? Are they impressions of appendages on or body segments dragged through the sand? d. Which of the following tracks would they most resemble?

Millipede track one

Millipede track two

Draw as best you can in or use your smart phone to “record” leg movement.

Microsoft word instructions: Use insert a shape (the one highlighted below is a good one to use).

The size of any shape can be modified. Use blue circles to modify size, yellow to modify angle and green to modify orientation.

Once you have a basic shape, copy and paste a number of strokes to indicate “foot” movement.

See example below.

You can also do the same in preview by choosing blank page and then using a small oval or line to indicate “steps” used by the millipede or simply draw leg movement on a blank sheet of paper and give to your instructor to scan before the next lab. Dr. Feaver will scan any paper that clearly identifies the author and has their email address and lab section on that paper.

7. CentipedesObtain a slide showing the poison gland of a centipede. Contrast the head

outline with that of the millipede you examined.

INSECTSInsects are the most successful land group.

Compare the tagmatization found in insects to that of the shrimp you photographed last week. Also compare the tagmatization found in insects to that of millipedes and crustaceans.

You are to observe "walking" in an insect. Which legs move together? Compare its movements to that of the pill bug and millipede.

Everyone should view darkling beetles and springtails and then choose one other insect to examine.

8. Description of Springtails or Collembola. Not quite insects!! Although considered hexapods (having six legs), why are

these not considered true insects? It is because their mouthparts are not free as in most insects. Go ahead and examine the head on high power

and compare the head of a springtail to that of a termite or true insect of about the same size.

Obtain a photograph of the springtail and beetle. Label antennae, head and abdomen in both species. Describe which body structure contains the legs. Springtails will “walk” but also “jump” or use their furcula. To see this structure, please view one of the slides we have available of Collembola.

The name Collembola, derived from the Greek "coll" meaning glue and "embol" meaning a wedge, refers to a peg-shaped structure, the collophore, on the underside of the first abdominal segment.  The collophore was once thought to function as an adhesive organ, now is thought to play a role in osmoregulation. These were once considered insects, now placed in a separate group under the Hexapoda, a group that also contains the insects. They are also known as springtails because of their forked jumping organ (the furcula) found on the fourth abdominal segment. 

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9/10. Darkling beetles and grasshoppers are true insect. You may use one or the either to observe walking in a typical insect. Choose one of these as your model organism.

10. Choose one of the following species to examine. Compare locomotion and tagmatization in one of these other species to that of the grasshopper or beetle. You do not have to remove the animals from their cages and can just if you wish watch them move in their home aquaria

a. Darkling Beetles larvae. Cultures tend to synchronize their development and so all our larvae are the same size and almost of the size that pupates. Please compare adults to related species of desert beetles of no adults are present in our cultures. Newly hatched larvae are almost microscopic and may molt 50 times or more before reaching pupation size.

b. Domino roaches

Adults are beetle mimics, possibly of Anthia sp. tiger beetles. Nymphs tend to be more roach like and to burrow during the day, These roaches feed primarily on dried leaves, but love small bits of protein-based pet foods and fruit.

c. Desert darkling beetles.Flightless beetles often seen trudging across trails and over sandy terrain. If bothered, the

beetle does a headstand, signaling that it's ready to squirt a noxious substance onto an assailant. The spray is foul to the nose, and isn't dangerous to people.

d. BessbugsThese harmless beetles live in and under moist, rotting wood. Bessbugs are paternal and adults will chew up wood and feed it to the young larvae. A common species is Odontotaenius disjunctus but our supplier does not identify their cultures. Adults stridulate by rubbing abdomen against the wings. Larvae stridulate with reduced third pair of legs–these scratch against other legs.”  We only have a few of these but they should walk on wet dirt in a large dish for you.

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11. Arachnids : Please examine a slide of a pseudoscorpion or hair follicle mite. a. Pseudo scorpions. Compare the tagmata of Pseudo scorpions to that found in insects and crustaceans. Verify your examination by obtaining a labeled photograph for your journal. Pseudo scorpions are predators feeding on ants, mites and small flies among other small arthropods. Many species spin silk from a gland in their jaws to make cocoons for mating, etc. They do have venom glands located within their palps.

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b. Note the adaptations for a parasitic life cycle on mites found on humans primarily in the hair follicles of eyelashes and eyebrows. Two species have been identified and we have slides of Demodex folliculorum. The adult mites are only about .4 millimetres long with an very elongated body. The mites can leave the follicles and walk around on the skin at night. Almost all adults over the age of 17 carry them. It is only in rare cases that the mites result in any skin eruptions.

The species that infects dogs however can result in serious disease (mange). Compare the structure of the hair follicle mite in your journal to that of a free living arachnid.

12. Parasitic insects:If time permits, look at the slides of lice. My daughter came home with these a few times from school. Lice are insects but modified structurally for their ectoparasitic lifestyle. There are three species that infect humans, identified by structure and habitat, hair, body or pubic area. Compare the structure of one of these species to those of the eyebrow mite. Make sure in your journal you note the species that you examined.