Kingdom Protista

      Protists are a diverse group of eukaryotic microorganisms. Historically, protists were treated as the kingdom Protista, which includes mostly unicellular organisms that do not fit into the other kingdoms, but this group is contested in modern taxonomy. Instead, it is "better regarded as a loose grouping of 30 or 40 disparate phyla with diverse combinations of trophic modes, mechanisms of motility, cell coverings and life cycles."

       The protists do not have much in common besides a relatively simple organization either they are unicellular, or they are multicellular without specialized tissues. This simple cellular organization distinguishes the protists from other eukaryotes, such as fungi, animals and plants.Some members of Kingdom Protista are unicellular, others are colonial, and yet others are multicellular. Note that in the colonial forms, all the cells are similar with similar, generalized functions, whereas in the truly multicellular species, the “body” of the organism consists of a variety of types of cells, each type with its own specialized function. These organisms are all eukaryotes (they have a true nucleus). They all need some kind of a water-based environment--which can be fresh or marine water, snow, damp soil, polar bear hairs--in which to live. All are aerobic and have mitochondria to do cellular respiration, and some have chloroplasts and can do photosynthesis. Most of them reproduce or grow by mitosis, and some reproduce by meiosis and fertilization. Many can form cysts in adverse conditions. Protists are a major component of plankton.

                Examples

• Paramecium
• Amoeba 
• Giardia
• Trichonympha

Kingdom Monera

             Monera is a kingdom that contains unicellular organisms without a nucleus (i.e., a prokaryotic cell organization), such as bacteria. The kingdom is considered superseded. The Kingdom Monera is the most numerous of all organisms, and makes up the only prokaryotic kingdom.  All of the Monerans share these characteristics:

• All bacteria are prokaryotes.  (lack a membrane bound nucleus)
• All bacteria are unicellular.  (only have one cell)
• They may be spherical (coccus), rodlike (bacillus), spiral (spirillum).
• On average, bacteria are 1 micrometre long and 0.5 micrometres wide.
• Bacteria are surrounded by a lipid membrane.
• A cell wall lies outside the cell membrane.
• Bacteria move by flagella, secreting slime or by axial filiments.
• Bacteria reproduce through binary fission, which is asexual.

      Examples: 

• Bacteria, 
• Nostoc, 
• Blue green algae, 
• Bacillus, 
• Halo bacterium ....  

Desert ecosystem

Desert Ecosystem


              Though a desert may seem like a barren land devoid of lifeforms, life does exist in this harsh environment. Numerous plants and animal species have adapted to these seemingly unsuitable conditions. In the desert ecosystem, climate is a deciding factor for the existence of lifeforms. In deserts, temperatures can reach up to 115° F during the day, and come down to 32° F at night. Such extreme temperature makes it difficult for lifeforms to survive in the deserts, unless they adapt to this harsh climate. Surprisingly though, many plants and animals have adapted themselves over the years, and have become an important part of the desert ecosystem today.

Definition: Desert Ecosystem
 
                In geographical studies, deserts are defined as regions wherein the average annual precipitation seldom exceeds more than 10 inches per year, and the amount of water lost to evapotranspiration is much more than the amount of water gained by precipitation. Like hot deserts, such as the Sahara and Mojave, there are cold deserts as well, the best example being Antarctica. One of the prominent difference between the two is the form of precipitation, which is snowfall in cold deserts and rainfall in hot deserts. Irrespective of whether it is a hot or a cold desert, the characteristic traits of both almost remain the same. It may comes as a surprise, but the areas which we refer to as hot deserts have a chilling temperature at night.

Desert Ecosystem: Animals
 
              Not many of us are aware of the fact that deserts are home to a number of species of kingdom Animalia. Biodiversity of the deserts is as unique as other biomes of the world. You might not see these animals as you see zebras and wildebeests in Africa, but they do exist and each of these species play a crucial role in the desert ecosystem food chain. Like in most of the other ecosystems, plants are the primary producers, while rodents, insects and reptiles which feed on these plants are the primary consumers. Then come the secondary consumers, who mainly comprise larger reptiles and insects which feed on primary consumers. At the top of the desert food chain are the apex predators in the form of birds and mammals. Most prominent members of the desert animals list include the Gila monster, chuckawallas, desert tortoise, rattlesnakes, hawks, ostriches, bobcat, kangaroo rats, mountain lions, etc. Most of these desert animals are nocturnal, i.e. active during the night, and spend the entire day burrowing. This adaptation helps them to fight the soaring temperatures that persist during the day. Water being scarce in deserts, these animals have also modified themselves to make the most of the available water. Some animals absorb water from plants, while others store it in their fatty tissues. Read more on adaptations in desert animals.

Desert Ecosystem: Plants
 

              When we talk about desert vegetation, most of us only think about cactus. However, we fail to understand that within cactus, there are different types which grow in different deserts of the world. These plants have have modified themselves to sustain in the desert environment. Some plants store water in the specialized tissues, while others have small leaves with hair like structures which reduce the evaporation of moisture. In North American deserts, barrel cactus is the most abundantly found cacti species, while other species include crimson hedgehog cactus, pancake prickly pear cactus, saguaro cactus, etc. Other cactus plants such as brittle bush, saltbush, creosote bush, desert ironwood, gravillias, Joshua tree, Mojave aster, Soaptree yucca, hanging chain cholla, etc., are also quite common in deserts. Read more on desert plant life.

Our ecosystem