Very valuable Animal Notes<\/p>\n
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Basic Structure of an animal<\/p>\n
The basic difference between an animal and a plant is that instead of being an autotroph they are heterotrophs. An animal can best be described as \u201c a multicellular, heterotrophic, and usually motile organism\u201d. The difference between unicellular and multicellular animals is that multicellular organism have tissues which allow for the division of labour done by cells.<\/p>\n
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Inverterbrates<\/p>\n
Basically, any animal (multicellular) without a backbone is an invertebrate. Invertebrates can live in aquatic, terrestrial and parasitic environments. They may range in size from the microscopic to mammoth squid.<\/p>\n
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Some benefits of inverterbrates\u2026(five)<\/p>\n
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But\u2026<\/p>\n
Many invertebrates can cause disease (five)<\/p>\n
Oiwee..<\/p>\n
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Importance of having three germ layers, is that each layer allows for cell specialization. With the formation oftissues, these germ layers can specialize to preform specific tasks. As the organism evolve, one notes an increase in functions of each germ layer.<\/p>\n
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For example<\/p>\n
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Symetry<\/p>\n
Symetry and life style<\/p>\n
Animals that tend to stay in one place will show no symetry (such as coral) or radial symetry such as sea anemome. Since these organisms live in one spot, they depend upon the flow of water to both provide food and distribute gametes. With the advent of movement, animals will shift to bilateral symetry. This means that they can hunt for food and muscles will be innervated by a nerve tissue.<\/p>\n
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Development of systems<\/p>\n
Linked to coelom<\/p>\n
The basic distinction of an animal is to eat, so tissues will be developed to eat food. If you have a simple surface area to volume ratio, there is no need to create systems for digestion. For example tape worms can absorb food across a simple single cell layer. Acoelomates tend to show simple strategies for digestion, such as filter feeding, or parasitic absorption. The planarian does have a simple gut that also doubles to move food in and out of the body. With the increase in locomotion there is a need for more food. The formation of a full digestive tract, such as pseudocoelomate nematod worms, allows for food to go in and out of the body by two pores. In addition, muscle movement within the body can work independently of external muscle. Please check previous notes for more facts about the coelom. With more food there is more waste, so there is development of excretory system.<\/p>\n
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Filter feeding<\/p>\n
Specialized cells to create current (collar cells)<\/p>\n
Specialised cells to form pores<\/p>\n
Less energy used to find food<\/p>\n
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Internal and external digestion<\/p>\n
External<\/p>\n
Simple guts to tubular guts<\/p>\n
Digestive enzymes to rapidly disolve food prior to being absorbed by<\/p>\n
Cells<\/p>\n
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Parasitism<\/p>\n
Adaptions<\/p>\n
Hooks and suckers<\/p>\n
Cutticle<\/p>\n
Proglottids<\/p>\n
No need for digestive system<\/p>\n
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Classification:<\/p>\n
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Porifera<\/p>\n
Sample : Sponges<\/p>\n
These are asymetric, filter feeding critters that almost look like rocks! In fact the ones at the aquarium are! These animals have three layers, although they are made from two germ layers. So sponges do have distinct cell types. The middle layer is made of spicules which form a skeletal system that protects and shapes the organism. The spicules are made of calcium carbonate which is hard enough to make\u2026rock..or fossils. Water is filter in through pore by collar cells. These cells use flagella to produce water current and gametes. Sponges reproduce asexually by budding. Since these animals are sedentary they depend upon the flow of ocean currents for food. Though this may be hazardous if the water is not pure, they do not have to expend a lot of energy to get food.<\/p>\n
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Cnidaria<\/p>\n
Sample: Hydra, Jelly fish, Sea Anenome<\/p>\n
These animals are radial in symetry. They eat by stinging their prey with nematocyst which in the case of the hydra can paralyze the prey. The interesting thing is that these same tentacles can also be used for fertilization, as in the jelly fish. Cnidarian some times have moving and sendentary stages. They usually have tentacles souronding a mouth. Organism such as the jelly fish can have both sexual and asexual forms.<\/p>\n
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Platyhelminthes<\/p>\n
Sample: Planaria , Flukes and tapeworms<\/p>\n
Flat worms can either be free living or parasitic. They show bilateral symetry and unique loss or gain of systems. Free living species show nerve tissue development with anterior ganglia and nerve cords. Planaria have both eyespots and sensory lobes. In comparison, parasitic form tend to show anterior specialization to adhere to the host, such as suckers or hooks. Free swimming Planaria show unique regenerative properties. Parasitic species such at tapeworms no longer need digestive tissue due to the environment they live in. However, to insure survival, they have mass producing proglottids. These segments have both male and female tissue to increase the rate and amount of eggs. Proglottids develop along the length of tape worm, with the mature ones being at the posterior end (which contain many eggs) and the immature ones being close to the scolex. Another type of parasitic worm are flukes such as the liver fluke. This parasite has a life cycle that start within the host stomach, moves to the intestines, then the liver and then the gall bladder\u2026so the parasite not only moves around outside the host, it also moves within the host!<\/p>\n
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Round worms.<\/p>\n
Samples: nematoda, hookworm, filarian worm,ascaris and trichinella<\/p>\n
We now enter the world of psuedocoelomates. Round worms can be free living or parasitic. They have complete digestive tracts with a mouth and an anus. Parasitic worms can specialize ectoderm tissue to form cutticle which prevents them from being digested. One of the most graphic round worm infections is elephantiasis, which is due to filarian worms. This parasite is associated with lymph vessel blockage which causes the body to swell to\u2026elephant proportions! The medical staff and worm symbol can be traced back to how this worm was once extracted from the skin by wrapping it around a stick. Life cycle of ascaris enters the body via the gut but eventually works its way to the lungs, via the blood to the liver to the heart. Each time the host coughs they reinfect themselves. To infect other hosts the eggs are excreted by adult worms in the gut. If the eggs and the adult are remain in one host, the spreading of the parasite is limited.<\/p>\n
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Some Vocabulary<\/p>\n
| Term<\/td>\n | Definition or example<\/td>\n<\/tr>\n |
| Coelom<\/td>\n | <\/td>\n<\/tr>\n |
| Budding<\/td>\n | <\/td>\n<\/tr>\n |
| Medusa<\/td>\n | <\/td>\n<\/tr>\n |
| Hermaphrodite<\/td>\n | <\/td>\n<\/tr>\n |
| Echinodermata<\/td>\n | <\/td>\n<\/tr>\n |
| Gastropoda<\/td>\n | <\/td>\n<\/tr>\n |
| Nematocysts<\/td>\n | <\/td>\n<\/tr>\n |
| Collar cells<\/td>\n | <\/td>\n<\/tr>\n |
| Flame cells<\/td>\n | <\/td>\n<\/tr>\n |
| Cutticle<\/td>\n | <\/td>\n<\/tr>\n |
| Polyp<\/td>\n | <\/td>\n<\/tr>\n |
| Vector<\/td>\n | <\/td>\n<\/tr>\n |
| peritoneum<\/td>\n | <\/td>\n<\/tr>\n |
| tentacles<\/td>\n | <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n Now using the text and notes, try and answer the following<\/p>\n <\/p>\n Big ideas in biology<\/p>\n Interactions<\/p>\n
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