BP 21 Lida Nguyen

From GGCWiki
Jump to: navigation, search


Location of Collection

Beaver Pond at GGC

Date of Collection

August 2012

Shannon-Wiener Index of Biodiversity


Daphnia 1.JPG Daphnia 2.JPG

Distinguishing Morphological Features of Order

  • Fused down-turned head
  • Head bears two pairs of antennae
  • Body is not segmented
  • Contains translucent carapace covering unsegmented thorax and abdomen
  • Single black median compound eye
  • Small mouthparts




Daphniidae (also known as water fleas)




Daphnia pulex

Geographical Distribution

It has a cosmopolitan distribution and is found throughout the Americas, Australia, and Europe.

Life Cycle

  • Can either reproduce sexually or by parthenogenesis (form of asexual reproduction in which growth and development of embryos occur without fertilization)
  • Reproduction period is usually from spring to end of summer
  • Can also produce eggs capable of overwintering.
  • One or more juveniles are nurtured in brood pouch inside carapace
  • Young are small copies of adults (there are no true nymphal or instar stages)
  • Must molt several times before reaching adulthood (usually takes about two weeks)
  • Fully mature females are able to produce new brood of young about every ten days under ideal conditions
  • Reproduction process continues while environmental conditions continue to support growth
  • Lifespan does not exceed one year and is very temperature dependent
  • Harsh conditions cause lifespan to decrease to six months

When winter approaches, in drought conditions, or at times of other extreme environmental conditions, production of new female generations comes to an end, and parthenogenic males are produced. With the production of males, sexual reproduction can take place instead of parthenogenesis.

During sexual reproduction, fertilized eggs (winter eggs) have an extra shell layer called the ephippium, which preserves and protects the egg inside from extreme environmental conditions until more favorable environmental conditions take place.

Sexual Dimorphism

Males tend to make up less than half the population. Males are much smaller in size compared to females and have a specialized abdominal appendage, which is used in mating to grasp a female from behind, pry open her carapace, insert a spermatheca, and fertilize the eggs. Although females are automatically larger than males, during harsh environmental conditions, females grow at a slower rate. This slower rate causes females to be much larger than they usually are during favorable conditions.

What it eats

They are typically filter feeders.

  • Unicellular algae
  • Protists
  • Bacteria
  • May sometimes consume tiny crustaceans and rotifers


They live in a wide range of aquatic habitats, ranging from acidic swamps to freshwater lakes, ponds, streams, and rivers.

Ecological Importance

They are considered threatened and are preyed upon by both vertebrates and invertebrates. The role of predation on these water fleas is extensively studied. In addition to the direct population ecological effects of predation, the process contributes to phenotypic evolution.

Economic, Agricultural, & Human Health Importance

In controlled environments or laboratories, they can be kept easily on a diet of yeast. Sometimes they are used in certain environments to test how toxins affect the ecosystem. This makes them an indicator genus. They are especially useful because of their short lifespan and reproductive capabilities. Due to their transparent exoskeleton, their internal organs can be easily studied while still alive. They are often fed to tropical fish, tadpoles, marine fish, and small amphibians.

PCR product: Gel Pictures

Gel pic 2.JPG

Sequence Data

  • Foward CO1:


  • Reverse CO1:


Personal tools