Wildlife of Planet Earth
"This planet is two-thirds ocean and one-third land. There are a variety of natural habitats with a lot of changes caused by the indigenous, human civilisation."
Planet Earth orbits a stable star at a relatively consistent distance. This produces surface temperatures that vary between approximately -20 and 40 degrees Celcius.
Water is an important resource, varying between solid (known as ice) and liquid form. Most of the known lifeforms on earth https://en.wikipedia.org/wiki/Tree_of_life_(biology) http://tolweb.org/tree/ are completely reliant on water. Solid water floats on liquid water: for this reason life is able to survive in the oceans and lakes without being crushed by ice.
The sun is another important resource with many plants http://www.theplantlist.org and animals taking their energy directly from its radiation. Plants and animals can also benefit indirectly from the sun by eating other plants and animals and also via the warming effect on the planet.
A year on earth is the time it takes to orbit once around the sun. The rotational axis is slightly tilted in its orbit: This causes seasonal fluctuations in climate because the sun heats better either the northern or southern hemisphere at different times of year. The indigenous population of humans call the warmest season summer and the coldest season winter. These annual changes cause some of the greatest wildlife spectacles as large numbers of animals move to avoid temperatures that are too hot or too cold for their survival.
Wildlife in the Seas
Much sealife is single-celled or small with vast populations meaning they are still significant in the ecosystem as a whole.
Sea cucumbers have approximately cylindrical bodies with a mouth surrounded by tentacles.
Bryozoans can look like seweed but on close inspection are made up of many tiny "moss animals" that group together, often looking like flattened leaves. By connecting together without covering each other they can gain cooperative benefits and all have direct access to the water to catch passing food.
Brittlestars and starfish have five-fold symmetry. Some starfish use water pressure to move their legs. This is one of many demonstrations that muscles (inherited by land animals from fish) are not the only solution to movement. Brittlestars seem to rely heavily on smell to navigate and interact with the world.
Chitons have segmented armour and can grasp onto a rock firmly for safety. The flattened body that extends beyond their armour has bristles that can sense the water around them. Some chitons have simple light sensors spread over their body with all the information combined possibly acting like a compound eye.
Annelid worms can create protective tubes of sand, discarded shell fragments and other detritus that stick up out of the seabed. As is common in the sea, they then have a mass of tentacles to feel for food.
Anemones have a fleshy body with tentacles that may be able to retract. They are not armoured but the tentacles can sting in defence. They also sting their own kind to push them away and maintain their own territory for feeding.
Green seaweed (not brown nor red seaweed) adapted to life out of the water, which is why land plants have green leaves. Fish adapted to life above the land and are the ancestors of reptiles, dinosaurs, birds and mammals, which is why land-based animals have symmetrical bodies. Some crustaceans have adapted to life on land which scientists suggest could be the origin of the land-based insects. Overall, the forms of life on land can be considered much less varied compared to life in the sea.
In the sea mobility is very good enabling regular migration patterns with the timescales varying from daily (in the case of plankton) to lifetime (in the case of salmon).
Wildlife on the Land
There are many mobile animals on planet Earth. Generally they are either migrants or residents or nomads. The origin of migratory behaviour can be guessed at but could be a response to the slow changes in climate meaning ideal summer and winter areas slowly drifted apart. The current habitat fragmentation due to damage from humans means a lot of land migration (particularly of mammals) is now prevented. Animals such as birds and butterflies can still fly through the sky. Navigation techniques are thought to include magnetism, geography, the position of the sun, polarisation of sunlight when it is cloudy and a growth behind the blindspot in birds which could act as a sextant. In cabbage white butterflies the temperature during larval development determines whether the individual flies north in spring or south in summer. Residents (that do not migrate) will often have survival techniques for the colder winter including using different food sources, cached food and hibernation. Nomads such as locusts, army ants and passenger pigeons continually strip one area and then move on.
Plants do no exhibit an obvious ordering into groups to the human eye. Much of their evolution is driven by an invisible chemical war and cooperation between themselves and other lifeforms such as insects and fungi. The highly visual differentiation by form and structure for interacting with the physical environment that is seen in, for example, mammals is not seen in plants. Most plant families include many forms including climbers, trees, shrubs, alpines and low-growing creepers.
Plants on planet Earth can be described as ruderals, competitors and stress-tolerators. Ruderals specialise in disturbed ground, gambling everything on reproduction rather than building strong plants. They rely on their large numbers of seeds flying around ready to take advantage of new cleared spaces. Competitors grow on fertile soils and stable habitats to build mighty empires. They aggressively maintain their empires with strong and well-defended structures, not worrying about seeds so much. Stress-tolerators are specially adapted to survive in poor-quality/hostile conditions.
There are as many as one and a half million species of fungi varying from microscopic and large colonies. Fungi are decomposers, symbionts and parasites. They are well known to humans because they decay food stored too long in the fridge, wood in homes and jet fuel in tanks. Damp conditions typically accelerate this decay. Huge numbers of spores can be produced by one fungus with the record annual spore release of several trillion held jointly by giant puffballs and large fruiting bodies of wood-rotting Basidiomycota. The network of hyphae can extend over many acres: For example, molecular marking has shown a giant Armillaria mycelium in a Michigan forest is approximately 1,500 years old and 10,000 kilogrammes in weight.
Lichen are a fungus in association with an alga or cyanobacteria. It is a lower plant that reproduces with spores and is typically found on rocks, trees and walls. A lichen can withstand very severe conditions such as drought, cold, heat and pollution in human cities. There are three types: (1) Branching "Frondose"; (2) Rounded, leaf-like "Fruticose" and; (3) Crusty type "Crustose". On rocks, trees and walls. Lichen might be the last complex lifeform seen as you travel to either geographic pole.
It has been suggested that because of the amount of between-species gene transfer that goes on, the bacteria can be viewed as a single global superorganism. Bacteria use simple chemical reactions to get their energy. They are often only one thousandth of a millimetre in length. They can be minute rods, discs or spheres. Bacteria field signs include large bubbles coming from the bottom of a pond and blue-ish will-o-the-wisps (because some bacteria use hydrogen and carbon dioxide to make water and methane), a subtle mistiness in water and a coloured smear on a rock.
Human scientists have deduced that viruses have arisen on multiple, independent, occasions. A virus is a parasite averaging 30nm long, which is approximately one hundredth the size of a bacteria. Many viruses, when in reproductive mode, can produce thousands of offspring per hour in each of the cells infected in a host. The association with a host can vary between a short one-time visit to lifelong fatal association. Viruses may have played a role in the evolution of the earliest lifeforms and have since integrated themselves into the web of life.
Advice About Wildlife Watching on Planet Earth
Wildlife watching is both a popular hobby and an area of scientific research. I have found many useful scientific resources for researching places to visit. Birdlife International http://www.birdlife.org/datazone/species has a database with interesting information about many birds from all around the world; I find the navigation awkward so I use the search facility. Bird lists for any part of the world can be generated from the Avibase http://avibase.bsc-eoc.org/ website. The Red List for endangered birds http://www.iucnredlist.org is also a good general reference website. Similarly, I find the Birdlife datazone http://www.birdlife.org/datazone is a good starting point to find lots of information: If you follow the links to the taxonomy section you will find their complete list of all the world's bird species which can be amazing to look at.
There are many free online hiking maps https://dzjow.com/2012/04/12/free-online-topographic-maps-for-hiking/ which you can find for yourself or follow this link to get more help. If you really want to explore, the wikipedia page about the largest protected wildlife areas in the world https://en.wikipedia.org/wiki/List_of_largest_protected_areas_in_the_world might inspire you if you want to do some extreme wildlife watching.
If, like me, you are often reliant on public transport I find seat61 http://www.seat61.com/ is a useful website. Another good site is rome2rio http://www.rome2rio.com/ although I often find their suggestions are overconfident and generic search facilities such as Google can do similar things. If you are travelling by aeroplane remember that if you have the time stopovers are a great way of adding variety and value to your adventures. General online travel resources https://en.m.wikivoyage.org/wiki/Main_Page http://www.cycletourer.co.uk can also be useful for planning a wildlife-watching trip.
Birdwatching is a popular hobby with many online resources including a complete review of all bird families http://creagrus.home.montereybay.com/list.html and many general sites http://fatbirder.com http://www.camacdonald.com/birding http://www.cloudbirders.com http://www.birdforum.net/opus created by keen birdwatchers. An inspiration to me many years ago were the books by Nigel Wheatley http://www.wheretowatchbirdsandotherwildlifeintheworld.co.uk/ who also has a website. Stephen Burch http://www.stephenburch.com/ has an excellent personal website with birdwatching and dragonfly-watching articles. Johannes Fischer http://gottatwitchemall.blogspot.co.uk/ has a blog with some inspiring articles. Peter Law https://ramblingsnscribblings.wordpress.com runs a blog with articles about his wildlife-watching adventures. A crafty way I have found to work out a good time of year to see birds a particular country is to go to https://www.cloudbirders.com/tripreport and use the "bar chart of reports by month" facility to see when others are visiting.
Mammal watching http://www.mammalwatching.com is also popular but I find information about it is less easy to find: This is one of the reasons I make a special effort to give good coverage of mammals within my writing.
Many companies run wildlife holidays http://www.wildlifeworldwide.com http://fieldguides.com/ http://greenwings.co/ http://www.tropicalbirding.com/tour-calendar/ https://www.naturetrek.co.uk all around the world; their websites can be an inspiration for places to go.
There are also many websites with cultural https://theculturetrip.com/ or backpacking https://www.nomadicmatt.com/travel-guides or travel https://www.lonelyplanet.com https://www.wanderlust.co.uk or general https://en.wikipedia.org/wiki/Main_Page or other information to help the wildlife watcher make the most of an adventure.
This article is part of the Nature Travel Guide and was published on October 19th 2018.
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