The point that should be made is that when something disrupts a food web, humans should try to understand and minimize the disturbance. Students should also come to recognize that humans, too, are part of this complex web of life. Food Chains and Webs All living organisms depend on one another for food. Analyze and interpret data to provide evidence for the effects of resource availability on organisms and populations of organisms in an ecosystem. Construct an explanation about how the different parts of the food chain are dependent on each other. Develop a model to describe the cycling of matter and flow of energy among living parts of the food chain.
Construct an argument, supported by evidence gathered through observation and experience, showing how changes to physical or biological components of an ecosystem affect populations.
Evaluate competing design solutions for maintaining biodiversity and ecosystem services. Answer questions about how pollution affects food chains by applying scientific principles to design a monitoring plan for minimizing the human impact on the environment. Answer questions about the interdependence of herbivores, carnivores and producers as members of a food chain.
Answer questions about how pollution affects food chains. Background A food chain is a simplified way to show the relationship of organisms that feed on each other. They also act as food, providing energy for other organisms. In the Great Lakes, most producers are phytoplankton, or microscopic floating plants. An example of phytoplankton is green algae. Large rooted plants, another type of producer, provide food and shelter for different organisms, fish and wildlife.
Primary Consumers The next level in the food chain is made up of primary consumers, or organisms that eat food produced by other organisms. Examples of primary consumers include zooplankton, ducks, tadpoles, mayfly nymphs and small crustaceans. Secondary Consumers Secondary consumers make up the third level of the food chain.
Secondary consumers feed on smaller, plant-eating animals primary consumers.
Classification system — Science Learning Hub
Examples of secondary consumers include bluegill, small fish, crayfish and frogs. Top Predators Top predators are at the top of the food chain. They can be carnivores or omnivores. Top predators typically sit atop the food chain without predators of their own.
Examples include fish such as lake trout, walleye, pike and bass, birds such as herons, gulls and red tailed hawks, bears—and humans! Food Webs In reality, many different food chains interact to form complex food webs. Some researchers today do not agree that dinosaurs gave rise to birds, and are working to falsify this theory, but so far the evidence for the theory has swamped their efforts.
If they were to conclusively establish that birds are more likely descended from another group Crocodylomorpha, the group containing crocodiles, has been suggested , that would be a major upheaval in our knowledge of phylogeny. One single well-preserved fossil bird unequivocably of Triassic age might shed some doubt on the theory of the maniraptoran affinities of birds. That would be a major find. Some bird-like fossils have been presented as Triassic birds, but so far have not held up under peer review. Such is the dynamic nature of science. So you may be thinking now, what are these striking resemblances between birds and other dinosaurs?
The ratite birds, three of which are pictured in this article, are quite similar to theropod dinosaurs. Some of the similarities may be superficial, but others may be too obvious to dismiss, and in any case all available data must be considered. We'll start with the "reptilian" similarities of birds. Like all other reptiles, birds have scales feathers are produced by tissues similar to those that produce scales, and birds have scales on their feet.
Also, birds lay eggs like other reptiles. The soft anatomy musculature, brain, heart, and other organs all are fairly similar; birds are more derived in some aspects owing partially to their endothermic metabolism and their ability to fly. There are numerous skeletal resemblances between birds and other reptiles; these form the basis of the cladistic analyses done by Gauthier and others. Coelurosaurian dinosaurs are thought to be the closest relatives of birds, in fact, birds are considered to be coelurosaurs.
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This is based on Gauthier's and others' cladistic analyses of the skeletal morphology of these animals. Bones are used because bones are normally the only features preserved in the fossil record. The first birds shared the following major skeletal characteristics with many coelurosaurian dinosaurs especially those of their own clade, the Maniraptora, which includes Velociraptor :.
Some researchers have raised issues that may seem to make the theropod origin of birds difficult to support, but these difficulties are more illusory than substantial. One proposed difficulty is the gap in the fossil record between the first known bird Late Jurassic and the dromaeosaurs, probable sister group of birds Early Cretaceous.
- Taxonomy (biology);
- Food Chains and Webs | Teaching Great Lakes Science.
- Are Birds Really Dinosaurs?.
- Enterprise Interoperability: I-ESA12 Proceedings (Iste).
- Working with case classifications.
- Poison Arrows: North American Indian Hunting and Warfare.
This overlooks the blatant fact that other maniraptoran coelurosaurs, such as Ornitholestes , Coelurus , and Compsognathus , are known from strata of Late Jurassic age. If other maniraptorans were there, it logically follows that the ancestors of dromaeosaurs were there. Fragmentary remains of possible dromaeosaurs are also known from the Late Jurassic.
Types of Relations
The opponents of the theropod hypothesis refuse to propose an alternative hypothesis that is falsifiable. This is probably because there are no other suitable candidates for avian ancestors. The problems cited by such opponents for theropods are often more serious for the "thecodont" pseudo-hypothesis. Finally, such opponents also refuse to use the methods and evidence normally accepted by comparative evolutionary biologists, such as phylogenetic systematics and parsimony. They rely more on an "intuitive approach," which is not a method at all but just an untestable gestalt impression laden with assumptions about how evolution must work.
The "controversy" remains an interest more of the press than the general scientific community. There are more interesting issues for scientists to explore, such as how flight performance changed in birds, what the earliest function s of feathers was were , when endothermy arose in some archosaurs, which group of theropods was ancestral to birds, how theropod ecology changed with the acquisition of flight, why some bird groups survived the Cretaceous extinction of other dinosaurs, etc.
Without its feathers, Archaeopteryx looks much like a small coelurosaur such as a dromaeosaurid or troodontid. The facts are resoundingly in support of a maniraptoran origin for birds; certainly a theropodan origin at the very least. So when you see a hawk diving to snatch a dove, or an egret darting for fish, or an ostrich dashing across the African savanna, know that you are gaining some insight into what the extinct dinosaurs were like.