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A miracle under the microscope: How does Daphnia pulex change its color in different waters?
Daphnia, especially Daphnia pulex, is one of the most common aquatic organisms and possesses amazing ecological adaptations. Whether in the milky white lakes of North America or the green ponds of Australia, the color of Daphnia changes with different water quality and nutritional status, which will be an important topic in ecological research.
Basic characteristics of Daphnia pulex
D. pulex is a tiny crustacean whose body structure may be difficult to distinguish, but is characterized by its tentacles and unique anatomy. Compared to other aquatic organisms, D. pulex has a six-segmented head and two pairs of tentacles. The second pair of tentacles is particularly developed, becoming a powerful swimming tool.
Color changes and associations with water bodies
The color variation of D. pulex is mainly related to the nutritional status of the waters it inhabits. According to ecological studies, D. pulex appear almost transparent in oligotrophic lakes, while in overly eutrophic waters they turn bright red due to the production of hemoglobin.
"The nutritional status and light levels of the water body have a direct impact on the color and growth of D. pulex."
Predator Impact
D. pulex also serves as a food source for a variety of predators. This predator pressure not only affects its population ecology, but also drives the evolution of its phenotype. Larger Daphnia tend to coexist with invertebrate predators because they are more susceptible to vertebrate predation, while small Daphnia adapt to the presence of vertebrate predators.
Environmental factors affect it
The nutrient balance in the environment is also a major factor affecting D. pulex. When nutrients are lacking in the water, it not only reduces the body size and growth rate of Daphnia, but may even affect its interaction with predators.
"In tree-shaded ponds, D. pulex experienced increased nutrient concentrations relative to carbon, which led to its body size increase."
The Secret of the Genome
D. pulex is also an important species in genomic research. It was the first crustacean to be sequenced, and its genome contains 31,000 genes, significantly more than the 23,000 to 25,000 genes in the human genome. Such a genome structure is not only highly efficient, but also a key gene combination for environmental adaptation. The changes in expression of these genes in response to environmental changes explain how D. pulex survives in different habitats.
Changes in reproduction methods
D. pulex has a variety of reproductive modes, including cyclical parthenogenesis and obligatory parthenogenesis. This change in reproduction mode allows D. pulex to flexibly adapt to survive when the environment changes.
ConclusionIn conclusion, Daphnia pulex is an organism that can adapt to a variety of waters, and its color change is not only a survival strategy, but also a microcosm of the interaction of the ecosystem. As these creatures reproduce in cycles and quickly adapt to environmental changes, we have to wonder: when future environmental changes put more pressure on organisms, how will these tiny aquatic organisms respond?
