Lab Manual Exercise #10A
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Ecological Principles #2

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Table Of Contents:

    9.   Plant Succession  
  10.   Food Productivity Of Ocean       
  11.   Food Productivity Of Land       
  12.   Adaptations Links
  13.   Some Definitions:
          A.  Plant Adaptations
          B.  Animal Adaptations
  14.   Major Biomes of N. America
  15.   Photographs Of Adaptations
  16.   Principles of Population Growth

9. Plant Succession

Succession: An orderly sequence of different types of vegetation in a given region.

Hydrarch: Plant succession starting on relatively shallow water, such as ponds and lakes, and culminating in a mature forest.

1.  Shallow Pond
2.  Marsh
3.  Meadow
4.  Forest
Submersed Plants
Cattails & Tules
Conifer Trees

Four stages of hydrarch succession in a shallow pond.

Xerarch Succession: Plant succession starting on bare ground or rock and culminating in a mature climax forest. The pioneer species, such as lichens and mosses, result in the gradual accumulation of soil. Forested slopes in the Sierra Nevada (Yosemite National Park) were once bare granite after the last major glacial period 12,000 years ago. Today these slopes contain dense forests of lodgepole pine (Pinus contorta ssp. murrayana), red fir (Abies magnifica var. magnifica) and mountain hemlock (Tsuga mertensiana). If you probe down through the thick layers of duff (needles, leaves, cone scales & branchlets) and soil, you will encounter a bedrock of solid granite.

1.  Lichens &
2.  Herbs &
3.  Perennials &
  4.  Forest  

Four stages of xerarch succession on bare ground or rock.

Retrogression: A phenomenon where succession reverts back to pioneer conditions, such as water or bare ground. Examples of retrogression are flood waters, fire and volcanic eruptions. Retrogression occurred on the slopes surrounding Mount St. Helens in southern Washington when the forest was reduced to bare ground.

Pioneer: Early stage in forest succession in which the seedling and sapling trees are shade intolerant and must have full sunlight to survive. The pioneer forest cannot perpetuate itself because its seeds fall into the shady understory of parental trees where the seedlings cannot survive. Examples of pioneer trees are the lodgepole pine (Pinus contorta ssp. latifolia) in the Rocky Mountains and the Douglas fir (Pseudotsuga menziesii) in the Pacific northwest.

Climax: The final stage of succession in a given region where the vegetation type is able to perpetuate itself. Climax trees are shade tolerant and able to develop from seedlings in the shady understory of parental trees. Examples of climax trees are the Engelmann spruce (Picea engelmannii) in the Rocky Mountains and western hemlock (Tsuga heterophylla) in the Pacific northwest. Climax forest trees in the local mountains of San Diego County include the white fir (Abies concolor) and incense cedar (Calocedrus decurrens).

10. Food Productivity Of The Earth's Land & Oceans

The Ocean As A Food Source For The World's Population

Approximately 71 percent of the Earth's surface is covered by ocean. In the late 1900s, fishing off the coast of Peru alone accounted for roughly 10 million metric tons of food annually, about 1/6 of the annual fish harvest from the world's oceans each year. [This was based on a total world harvest of 60 million metric tons per year.] If this data is accurate, then why can't we obtain fish from other vast areas of the ocean to supply our growing populations with an unlimited food resource? The truth is that most of the oceans of the world are relatively unproductive in terms of high fish yields. The reason that the coast of Peru (and several other regions of the world) are so productive is related to currents and the upwelling of deep waters. The upwelling brings vital nutrients to the surface and provides for a productive food web with rich populations of plankton and fish. It has been estimated that the total potential for ocean fishing may be 120 million metric tons per year. With an annual fish harvest of approximately 60 million metric tons in the late 1900s, we may be able to double out annual fish harvest; however, with an annual world population growth that is doubling every 35 years, how long will this last. In addition, there is a grave danger in overfishing a region. If the fish populations are reduced too much, they may not be able to recover. The creation of artificial reefs and fish breeding programs (fish hatcheries) are promising areas of research to increase fish populations, but even these will only supply a short term answer to the human population explosion.

Another potential source of food from the ocean is plankton, microscopic photosynthetic organisms (phytoplankton) and microscopic animal life (zooplankton). It has been estimated that the North Atlantic alone has an annual production of plankton greater than 10,000 world crops of rice and wheat. But there are some monumental logistic and biological problems associated with the large scale harvesting of ocean plankton. It would be necessary to filter a million gallons of ocean water to obtain only a pound of plankton. The plankton must be preserved or refrigerated immediately; otherwise the delicate cells will decay rapidly when they are exposed to the air. And what about all the higher trophic levels of the ocean food web that depend on the plankton? Considering the inefficiency of ecological food chains with an average decrease of 90 percent at each trophic level, it takes about 2500 pounds of phytoplankton to support a mere half pound of tuna! In addition it has been estimated that 70-90 percent of the Earth's atmospheric oxygen is produced by the phytoplankton, primarily diatoms. Phytoplankton live in the photic zone, with an average depth of suveral hundred feet. Multiplying this depth by the surface area of the world's oceans accounts for an astronomical volume of phytoplankton. Harvesting plankton from the ocean is like extracting gold, there is a lot of it, but the logistic problems are formidable.

11. The Land As A Food Source For The World's Population

Although it has be estimated that there are only about 10 billion acres of tillable land on the world's continents (only a fraction of the total area of the world's oceans), this is where most of the food for humans is derived. In terms of mass (tons), the total aquaculture harvest from the world's oceans, including seaweeds, fish and mollusks, is less than 1/600th of land agriculture. Food from the land includes grains (cereals), legumes, root crops such as potatoes and yams, vegetables, beef and poultry. But even our food from the land is not an infinite resource. Considering that 1/4th acre of land is required to provide food for one person per year, then 10 billion acres of tillable land would support 40 billion people (10 billion acres divided by 0.25 acres per person). With a world population of just over 6 billion at the onset of the 21st century (and a 2% annual growth rate), the carrying capacity for humans (40 billion) may be reached in roughly one century. The following two links show real time counters for the world population. Every second, five people are born and two people die. With a population increase of three people per second, at the end of a 50 minute Biology 100 lecture the world population will have increased by 9,000 people.

12. Plant & Animal Adaptations Links

Ecological Adaptations:

Poison Dart Frogs
Population Growth
Life On Salt Lakes
Pollination By Bats
Life On Sand Dunes
Principles Of Ecology
Pollination By The Wind
Hummingbird Pollination
Snow Algae: Life On Ice
Hitchhikers:  Cockleburs
Hitchhikers: Devil's Claw
Hitchhikers: Most Efficient
Strangler Figs And Banyans
Dispersal By Ocean Currants
Dispersal Of The Sandbox Tree
Bat Pollination Of Sausage Tree
C-4 Photosynthesis In Purslanes
Rock Lichens And Desert Varnish
Vegetative Structures--Mangroves
CAM Photosynthesis In Succulents
Fire Ecology: Ashes To Wildflowers 

Insect & Plant Relationships

Insect-Eating Plants
The Amazing Antlions
The Marine Seagrasses
The Yucca And Its Moth
The Acacia And Its Ants
Diversity In The Acacias
Mexican Jumping Beans
California Jumping Galls
Mycotrophic Wildflowers
The Datura And Its Moth
Galls: Growths On Plants
Eucalyptus & Lerp Insect
Sexual Suicide In Animals
The Truth About Cauliflory
Fig Wasp Gall Controversy
Calimyrna Fig And Its Wasp
Pollination In Dioecious Figs
Cyanobacteria & Water Ferns
The Fig/Fig Wasp Relationship
Sex Determination In Edible Fig
 Stinking Flowers Pollinated By Flies 

13. Some Definitions

A. Plant Adaptation Definitions

Sclerophyllous: Tough, leathery leaves with compact cell structure, few air spaces and thick or multiple epidermis. Sclerophyllous leaves are adapted to conserve water (prevent excess transpiration) in arid environments. They often have a thick cuticle with the stomata confined to the lower epidermis or in crypts. This is the characteristic leaf adaptation of chaparral shrubs, such as scrub oak (Quercus) and manzanita (Arctostaphylos).

Microphyllous: Small leaves with reduced surface area. Because of their small size, microphyllous leaves typically have reduced water loss through transpiration. Microphyllous leaves are characteristic of xerophytic plants of the chaparral and desert biomes, including redberry (Rhamnus), smoke tree (Psorothamnus) and Acacia.

Drought Deciduous: Shrubs and trees of arid desert biomes in which the leaves are shed during prolonged periods of drought. During this extended drought season the plants become dormant. The classic example of this shrub in the desert regions of southern California and Baja California are ocotillo and the boojum tree (Fouquiera).

Stomata: Openings (pores) in the epidermis of leaves and stems which provide for gas exchange with the atmosphere. The opening is controlled by the size and shape of paired guard cells on either side of the stoma.

Xerophyte: A plant adapted for survival in soil with a limited supply of water. Capillary water is absent from the surface horizons of the soil for extended periods of time. Some xerophytes, such as cacti and succulents, store water in their stems to survive extended periods of extreme drought. Cactus spines are modified leaves which provide protection against browsing animals. Because photosynthetic leaves are absent from most mature cactus plants, photosynthesis occurs within chloroplasts in the stems. In addition, cactus plants typically inhabit well-drained alluvial slopes and have shallow, surface roots to absorb the scant rainfall.

A classic xerophyte leaf: Magnified view of a Yucca leaf cross section showing dense cluster of fiber cells (pinkish-red cells with very small lumens). Note the thick, waxy layer (cuticle) along the upper side of the leaf that prevents desiccation in a hot desert climate. Also note the deep, sunken stomata with a pair of guard cells at the bottom (red square). Sunken stomata reduce desiccation because the guard cells and stomata (pores) are located in a deep pit (crypt). The leaves can carry on gas exchange through their stomata without being directly exposed to the hot sun and drying winds. [Magnified Approximately 400X.]

Capillary Water: Water occupying the spaces between soil particles. This is the only water available to plant root systems.

Hydrophyte: A plant living in water or extremely wet soil (above field capacity). Hydrophytes include cattails (Typha) and tules or bulrushes (Scirpus). The stems of these hydrophytes contain tubular air spaces that allow oxygen to reach the root systems in muddy soil saturated with water.

See Bulrushes (Scirpus californicus) at Jack's Pond

Field Capacity: Maximum water that the soil can hold. This term refers to soil that is completely saturated with water.

Mesophyte: A plant living in soil with adequate soil moisture during the growing season. Mesophytes typically require regular watering in order to provide adequate capillary water during the dry months. Most of the plants in southern California gardens are mesophytes.

Halophyte: A plant adapted to soil or water containing a high salt concentration. The root cells contain a salt concentration higher than the water they are growing in. Since they are hypertonic compared with the water or soil, the root cells can take in water molecules and do not become plasmolyzed. Good examples of halophytes are the seagrasses, red and black mangroves (Rhizophora and Avicennia), salt grass (Distichlis) and salt bush (Atriplex). There are also species of bacteria and algae that are extremely halophilic (salt-loving), living in saturated brine and salt crust.

See Red Halobacteria In Salt Lakes
See Article About Marine Seagrasses

Pollination: The transfer of pollen from the anther to the receptive stigma of a flower. In self pollination, pollen is transferred from the anther to the stigma on the same plant. In cross pollination, pollen goes from the anther of plant A to the stigma of plant B. Insect pollinated flowers are typically fragrant with sweet nectar and brightly colored petals. Wind pollinated flowers typically do not have showy petals and produce copious airborne pollen. Since cross pollination involves two different plants, it results in more genetic variation. Plants have evolved many interesting methods of cross pollination. Some fascinating examples of pollination are shown in the following hyperlinks:

Hyperlinks About Pollination

Hymenopteran Seduction: Several remarkable examples of pollination involve the seduction of male wasps and bees by orchid flowers. Flowers of the Australian orchid Cryptostylis leptochila resemble a female ichneumon wasp. The male ichneumon wasp attempts to copulate with the flowers, thus insuring cross pollination as he mounts the blossoms. Other species of Cryptostylis orchids also entice male wasps to visit their blossoms for pseudosexual encounters. Orchids of the genus Ophrys are well-known for their flowers that mimic bees and wasps. The Mediterranean orchid Ophrys fusca seduces a male bee before the female bees have emerged from their pupal cases. The following image shows an uncanny "face" on this vanda orchid. With some imagination, the flower superficially resembles the head and front legs of an insect. Whether hymenopterans perceive this flower as an insect is pure speculation by this author.

This beautiful orchid native to Madagascar is often called the "Darwin orchid" (Macroplectrum sesquipedale), also known as Angraecum sesquipedale. In fact, to reach the nectar of this orchid requires a 30 centimeter (eleven inch) proboscis to penetrate the long nectar spur (white arrow). Long before it was found in nature, both Charles Darwin and Alfred Wallace (founding fathers of the principles of evolution) predicted that it would be a long-tongued hawk moth.

Whirling Nut (Gyrocarpus)
Dispersal: The movement of seeds and seed-bearing
fruits away from the parent plant by wind, birds, water
and mammals. One of the most ingenious methods of
wind dispersal is the remarkable "whirling nut" in the
genus Gyrocarpus. Fungi also have some interesting
and unusual methods of spore dispersal.

Water Dispersal Of Seeds & Fruits

Wind Dispersal Of Seeds And Fruits

Hitchhiker Dispersal Of Seeds & Fruits

Other Mechanisms Of Seed & Fruit Dispersal

Dispersal Of Fungal Spores

The common naturalized lawn weed in southern California called creeping woodsorrel (Oxalis corniculata) is a good example of mechanical dispersal. The minute seeds are forcibly ejected as the fuzzy capsules split open. When mowing a lawn or walking through a patch of creeping woodsorrel, the seeds are often ejected onto your clothing. This phenomenon is especially evident when wearing a light-colored shirt. This widespread weed is apparently native to the Old World.

Oxalis pes-caprae: Another naturalized species in California

Lignotuber: A subterranean woody stump or burl from which many chaparral shrubs resprout following a wild fire. The large tuberous burls of wild cucumber (Marah macrocarpus) are one of the first plants to appear on burned hillsides following a brush fire in southern California.

See The Woody Lignotuber Of Chamise
See Huge Tuberous Burl Of Wild Cucumber

Serotinous: Seed cone of a conifer that remains unopened and persistent on the tree for many years. The heat of a wild fire causes the cone scales to gradually open, thus liberating the seeds on the ash-covered slopes. The ideal seed bed requirement for pines of this type are: (1) Full sunlight, (2) elimination of duff layer (dead leaves and branchlets) which inhibit germination of pine seeds, (3) creation of a bare, mineral (ashy) soil which is ideal for seed germination, (4) elimination of competing chaparral shrubs with terpene oils that inhibit germination, and (5) elimination of certain soil fungi that cause "damping off" disease in pine seedlings. Some fire-adapted Australian shrubs such as Banksia and Hakea have seed-bearing, conelike capsules and pods that open after a fire.

See The Serotinous Cones Of Knobcone Pine
See The Serotinous Seed Capsule Of Banksia

Epiphyte: A plant that grows upon another plant for support or to reach sunlight. Some epiphytes, such as strangler figs, sea heart vines and morning glories, can literally shade out the host plant.

See Strangler Figs & Banyans
Sea Heart: Giant Legume Vines
Morning Glories: Beautiful Vines

Bromeliad: An epiphyte in the pineapple family (Bromeliaceae) which is able to trap rainwater in its rosette of leaves. Spanish moss (Tillandsia usneoides) is a common epiphyte in the southeastern United States. California Spanish moss is the lichen (Ramalina menziesii).

A Brazilian bromeliad of the genus Neoregelia. The basal rosette of leaves traps rainwater for this interesting epiphytic species.

See The Bromeliad Called Spanish Moss
See The Lichen Called Spanish Moss

Insectivorous Plant: A plant that traps and absorbs nitrogen from the bodies of dead insects. But why would some insectivorous plants need an additional supply of nitrogen, particularly when they are living in organically-rich bogs? The answer to this question may involve the pH of the water and soil that is too acidic for nitrifying bacteria that convert ammonia from protein decay into nitrite and nitrate ions. This important bacterial process is called nitrification. The nitrite and nitrate ions made available by the bacteria are readily absorbed by the roots of plants. If the nitrification process is impaired, there could actually be a shortage of these nitrite and nitrate ions; hence, the carnivorous plants have evolved a mechanism to obtain a supplemental supply of nitrogen.

Read About Insect-Eating Plants

Nitrogen fixation: A remarkable prokaryotic skill in which inert atmospheric nitrogen gas is converted into ammonia. Through another bacterial process called nitrification, the ammonia is converted into nitrites and nitrates, thereby making the vital element nitrogen readily available to the roots of higher plants. Since this process commonly occurs in the root nodules of legumes, farmers often rotate their crops with leguminous species (such as alfalfa and clover). Nitrogen fixation is also accomplished by a number of species of microscopic cyanobacteria, some of which live symbiotically in nonleguminous plants, including the leaves of water fern (Azolla), "poor man's umbrella" (Gunnera), and the roots of cycads. The actual sites of nitrogen fixation in the cyanobacteria are special cells called heterocysts. The roots of alder trees (Alnus), wax myrtle (Myrica) and California lilac (Ceanothus) contain nitrogen-fixing actinomycetes rather than eubacteria. Nodules of the actinomycete Frankia on alder roots greatly resemble the Rhizobium nodules of legumes.

Note: Here is a more accurate update for the above equation:

N2 + 8 H+ + 8e- +16 ATP + 16 H2O = 2 NH3 + H2 + 16 ADP +16 Pi

The fowing explanation is from Jim Deacon of the Institute of Cell and Molecular Biology, The University of Edinburgh.

Two molecules of ammonia are produced from one molecule of nitrogen gas. The reaction requires 16 molecules of ATP and a supply of electrons and protons (hydrogen ions) plus the enzyme nitrogenase. Nitrogenase consists of two proteins, an iron protein and a molybdenum-iron protein. The reaction occurs while N2 is bound to the nitogenase enzyme complex. The Fe protein is first reduced by electrons donated by ferredoxin. Then the reduced Fe protein binds ATP and reduces the molybdenum-iron protein, which donates electrons to N2, producing HN=NH. In two futher cycles of this process (each requiring electrons donated by ferredoxin) HN=NH is reduced to H2N-NH2, and this in turn is reduced to 2 NH3. Depending on the type of microorganism, the reduced ferredoxin which supplies electrons for this process in generated by photosynthesis, respiration or fermentation.

Actinomycetes include a large group of filamentous, fungus-like soil bacteria. They form long, threadlike, branched filaments that resemble gray spiderwebs throughout compost piles. In fact, the characteristic earthy smell of compost and recently overturned rotten logs in a forest is caused by thriving populations of actinomycetes. Electron microscopy and other studies have shown unequivocally that these organisms are bacteria and not fungi. Some authors refer to actinomycetes as actinobacteria and place them in their own phylum.

Poor man's umbrella (Gunnera insignis) in the cloud forest of Costa Rica. Species in the genus Gunnera contain symbiotic nitrogen-fixing cyanobacteria (Nostoc) within special tunnels in their leaf petioles. Like other cyanobacteria, the nitrogen fixation occurs within special cells called heterocysts.
Two Species Of California Lilac (Ceanothus)
Nitrogen Fixation and Nitrification Defined
Cyanobacteria In The Water Fern (Azolla)
Cyanobacteria In The Roots Of Cycads
See Additional Photos Of Cycads

B. Animal Adaptation Definitions

Hilltopping: A phenomenon where populations of insects fly upslope and converge at the summit of a hill. Hilltopping is common in San Diego County and provides an opportunity for male and female insects to meet and mate with each other.

Hilltopping: A Way For Sexually Active Insects To Meet Each Other

Warning Coloration: Insects with an obnoxious quality (at least to would-be predators), such as bad taste, bad smell or powerful sting, often exhibit bright colors to warn of their presence. Warning coloration is well developed in the insect order Hymenoptera, including bees and wasps. Small poison dart frogs of the tropical rain forest also exhibit warning coloration. These frogs contain very toxic neurotoxic alkaloids in their skin. Their coloration (called aposematic coloration) is an adaptation for diurnal foraging in which predators can easily recognize and avoid these poisonous amphibians. The brightly colored banding pattern of the Arizona coral snake is another example of warning coloration. This small snake is a member of the cobra family (Elapidae) and contains a very potent neurotoxin.

Warning Coloration In Poison Dart Frog
See Brightly Colored Poison Dart Frogs

Mimicry: One animal (called a mimic) that is perfectly palatable to its predator resembles another animal (called the model) that is quite disagreeable to the same predator. There are actually two types of mimicry: Batesian and Mullerian. Mimicry in which the mimic is essentially defenseless is called Batesian mimicry. A harmless moth (Aegeria) is a Batesian mimic because it is incapable of stinging another animal, but yet it resembles the yellow jacket wasp (Vespula). Several species of nonvenomous snakes of the western United States, including the milk snake, mountain king snakes and Colorado Desert sand snakes all have colorful banding patterns superficially resembling the venomous Arizona coral snake. Mimicry in which the mimic shares the same defensive mechanism as the model is called Mullerian mimicry. The yellow jacket wasp and bumblebee (Bombus) are Mullerian mimics because they both have bright yellow and black colors and use powerful stings as a defensive mechanism.

The banded sand snake (Chilomeniscus cinctus) is remarkably adapted  
for rapid movement through soft sand. Although it is harmless, this colorful
banded snake is sometimes mistaken for a very poisonous coral snake. If
you consider the Arizona coral snake a model and the sand snake a mimic,
this would be an example of Batesian mimicry.

Mimicry in coral snakes is complicated. There are a number of species of New World coral snakes belonging to two separate families, some poisonous and some nonpoisonous. Coral snakes of the cobra family (Elapidae) are generally poisonous, although the degree of toxicity varies with different species. In addition, some moderately poisonous species have a more aggressive defensive behavior compared with certain dangerously poisonous species. Coral snakes of the Colubridae are generally not poisonous, but have banding patterns that greatly resemble the poisonous species. The similarity of poisonous coral snakes to one another falls under the heading of Mullerian mimicry because model and mimics are poisonous to their predators.

Can you recognize which of these five banding patterns is typical of the dangerously poisonous Arizona coral snake? Only one of these five snake patterns has a venom capable of killing an adult human. The other four patterns are examples of Batesian mimicry. If you guessed correctly on the banding pattern of the poisonous species, please do not feel overconfident in identifying all coral snakes and their mimics. When it comes to venomous New World coral snakes, only people who understand the taxonomy of these snakes should be handling them. [This logic also applies to eating potentially toxic mushrooms in the wild.] There are definitely exceptions to the above poisonous banding patten in some tropical American species. See the following reference: Mimicry in Plants and Animals by Wolfgang Wickler (1968), World University Library, McGraw-Hill Book Company, New York.

A poisonous coral snake (Micrurus frontalis) native to Brazil. The classic rhyme "red bordered by yellow, kills a fellow" does not apply to this species. Other rhymes for identifying poisonous coral snakes are also useless, such as "red touching yellow, kills a fellow," and "if its nose is black, it's bad for jack."

Mating Coloration: Bright colorations among the males of some animals (particularly the plumage of birds) gives the male a definite advantage in sexual selection and mate attraction. Mating coloration and behavior of the most "fit" and aggressive males serves to stabilize the population density because only the most sexually select males are able to mate with females of the species.

Cryptic: Concealing form and coloration which enables a species to avoid its natural predators by camouflage. Good examples of this adaptation are the katydid, walking stick and tomato hornworm. The spittlebug secretes a foamy mass to conceal itself on a branchlet.

See Photographs Of Camouflage In Animals
See The Camouflaged Larva Of A Hawkmoth
See The Strange Foamy Froth Of A Spittlebug

Disruptive Markings: The markings on some insects, reptiles and mammals make it difficult to distinguish them from shadows and branches or from other members clustered together. The stripes on a zebra may appear quite distinctive, but to a colorblind lioness it is difficult to single out an individual zebra among a dense population in the African grasslands.

Fossorial: Insect legs adapted for digging or burrowing. Examples of fossorial legs include the mole cricket and Jerusalem cricket.

Raptorial: Insect leg adapted for grasping its prey. Examples of raptorial front legs include the preying mantis, giant water bug and ambush bug.

Saltatorial: Insect leg type adapted for jumping. The grasshopper has enlarged rear saltatorial legs.

Cursorial: Long, slender legs adapted for running swiftly, such as the ground beetle, tiger beetle and cockroach.

Common calosoma (Calosoma semilaeve), a large beetle that runs free during daytime hours in search of prey. With its long, slender, cursorial legs it runs very fast. When disturbed or threatened it emits a foul oder that smells like burning electrical insulation.

Swimming Leg: Flattened, hair-covered insect leg, characteristic of streamlined water beetles. The water beetles use their legs like oars.

Southern California Arthropods
See The Infamous Preying Mantis
See The Unusual Jerusalem Cricket

Echolocation: Method of navigation used by bats while they emit high frequency sound waves during flight. This is similar to the principle of sonar.

Metabolic Water: Water produced as a by-product of metabolic reactions, such as the water produced from the oxidation of lipids in the diet of the kangaroo rat. Lipid molecules (including fats and oils) contain a high ratio of hydrogen atoms which combine with oxygen to form water. This is how the kangaroo rat survives in an arid environment.

Zygodactyl: Bird foot adapted for clinging and climbing on the vertical bark of tree trunks. The woodpecker has this type of foot.

Diastema: A wide gap in the mouth of a rodent and lagomorphs (rabbits) that separates the incisors from cheek teeth (molars).

Sand Swimming: A method of moving rapidly through sand, such as the Colorado Desert fringe-toed lizard.

Life On Southern California Sand Dunes

Giant Water Bugs: Although these large insects have a voracious appetite, females instinctively lay their eggs on the male's back.

Giant water bugs (Abedus indentatus), affectionately called "toe biters" by barefooted swimmers. These large bugs of the family Belostomatidae cling motionless to underwater plants and debris in southern California streams. They periodically come to the surface to replenish their air supply carried in a bubble under the wings. With their poweful raptorial front legs they catch other aquatic insects, tadpoles and even small fish. Females typically deposit their eggs on the backs of the males. Brooding males provide for the needs of the eggs by exposing them to air and an intermittent flow of water. In addition, the eggs are protected and are not accessible to the ravenous males.

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