Herbivores can be further classified into frugivores fruit-eaters , granivores seed eaters , nectivores nectar feeders , and folivores leaf eaters. Examples of herbivores : Herbivores, such as this a mule deer and b monarch caterpillar, eat primarily plant material.
Some herbivores contain symbiotic bacteria within their intestines to aid with the digestion of the cellulose found in plant cell walls. Omnivores are animals that eat both plant- and animal- derived food. They can only eat things that are moderately easy to acquire while being moderately nutritious.
For example, most omnivores cannot live by grazing, nor are they able to eat some hard-shelled animals or successfully hunt large or fast prey. Humans, bears, and chickens are examples of vertebrate omnivores; invertebrate omnivores include cockroaches and crayfish.
Examples of omnivores : Omnivores such as the a bear and b crayfish eat both plant- and animal-based food. While their food options are greater than those of herbivores or carnivores, they are still limited by what they can find to eat, or what they can catch. Carnivores are animals that eat other animals. Obligate carnivores are those that rely entirely on animal flesh to obtain their nutrients; examples of obligate carnivores are members of the cat family.
Facultative carnivores are those that also eat non-animal food in addition to animal food. Note that there is no clear line that differentiates facultative carnivores from omnivores; dogs would be considered facultative carnivores.
Examples of carnivores : Carnivores such as the a lion eat primarily meat. The b ladybug is also a carnivore that consumes small insects called aphids. Invertebrate digestive systems include a gastrovascular cavity with one opening or an alimentary canal with a true mouth and anus.
Invertebrate digestive systems : a A gastrovascular cavity has a single opening through which food is ingested and waste is excreted, as shown in this hydra and in this jellyfish medusa. Animals have evolved different types of digestive systems break down the different types of food they consume. Invertebrates can be classified as those that use intracellular digestion and those with extracellular digestion.
The simplest example of digestion intracellular digestion, which takes place in a gastrovascular cavity with only one opening. Most animals with soft bodies use this type of digestion, including Platyhelminthes flatworms , Ctenophora comb jellies , and Cnidaria coral, jelly fish, and sea anemones. Invertebrates with Extracellular Digestion : Invertebrates like grasshoppers have alimentary canals with specialized compartments for digestion. Their food is broken down in their digestive tract extracellular digestion , rather than inside their individual cells intracellular digestion.
Ingested material enters the mouth and passes through a hollow, tubular cavity. The food particles are engulfed by the cells lining the gastrovascular cavity and the molecular are broken down within the cytoplasm of the cells intracellular. The alimentary canal is a more advanced digestive system than a gastrovascular cavity and carries out extracellular digestion. Most other invertebrates like segmented worms earthworms , arthropods grasshoppers , and arachnids spiders have alimentary canals.
The alimentary canal is compartmentalized for different digestive functions and consists of one tube with a mouth at one end and an anus at the other. Once the food is ingested through the mouth, it passes through the esophagus and is stored in an organ called the crop; then it passes into the gizzard where it is churned and digested. From the gizzard, the food passes through the intestine and nutrients are absorbed.
Because the food has been broken down exterior to the cells, this type of digestion is called extracellular digestion. The material that the organism cannot digest is eliminated as feces, called castings, through the anus. Most invertebrates use some form of extracellular digestion to break down their food. Flatworms and cnidarians, however, can use both types of digestion to break down their food. Vertebrates may have a single stomach, several stomach chambers, or accessory organs that help to break down ingested food.
Vertebrates have evolved more complex digestive systems to adapt to their dietary needs. Some animals have a single stomach, while others have multi-chambered stomachs. Birds have developed a digestive system adapted to eating un-masticated un-chewed food. Humans and many animals have a monogastric digestive system. The process of digestion begins with the mouth and the intake of food. The teeth play an important role in masticating chewing or physically breaking down food into smaller particles.
The enzymes present in saliva also begin to chemically break down food. The esophagus is a long tube that connects the mouth to the stomach. Using peristalsis, the muscles of the esophagus push the food towards the stomach.
In order to speed up the actions of enzymes in the stomach, the stomach has an extremely acidic environment, with a pH between 1. The gastric juices, which include enzymes in the stomach, act on the food particles and continue the process of digestion. In the small intestine, enzymes produced by the liver, the small intestine, and the pancreas continue the process of digestion. The nutrients are absorbed into the blood stream across the epithelial cells lining the walls of the small intestines.
The waste material travels to the large intestine where water is absorbed and the drier waste material is compacted into feces that are stored until excreted through the rectum. Mammalian digestive system non-ruminant : a Humans and herbivores, such as the b rabbit, have a monogastric digestive system. However, in the rabbit, the small intestine and cecum are enlarged to allow more time to digest plant material. The enlarged organ provides more surface area for absorption of nutrients.
Birds face special challenges when it comes to obtaining nutrition from food. They do not have teeth, so their digestive system must be able to process un-masticated food. Birds have evolved a variety of beak types that reflect the vast variety in their diet, ranging from seeds and insects to fruits and nuts.
Because most birds fly, their metabolic rates are high in order to efficiently process food while keeping their body weight low. The stomach of birds has two chambers: the proventriculus, where gastric juices are produced to digest the food before it enters the stomach, and the gizzard, where the food is stored, soaked, and mechanically ground. The undigested material forms food pellets that are sometimes regurgitated.
Most of the chemical digestion and absorption happens in the intestine, while the waste is excreted through the cloaca. Bird digestive system : The avian esophagus has a pouch, called a crop, which stores food. Food passes from the crop to the first of two stomachs, called the proventriculus, which contains digestive juices that break down food. From the proventriculus, the food enters the second stomach, called the gizzard, which grinds food.
Some birds swallow stones or grit, which are stored in the gizzard, to aid the grinding process. Birds do not have separate openings to excrete urine and feces. Instead, uric acid from the kidneys is secreted into the large intestine and combined with waste from the digestive process. This waste is excreted through an opening called the cloaca.
Ruminants are mainly herbivores, such as cows, sheep, and goats, whose entire diet consists of eating large amounts of roughage or fiber. The small intestine is where most of the digestion and absorption of nutrients takes place.
There are millions of tiny finger-like projections lining the small intestine called villi pronounced: "VILL-ee". These villi aid in the absorption of nutrients. Secretions from the liver, pancreas, and gallbladder are emptied into the small intestine and also aid in the digestive process.
When a portion of the intestines do not have adequate blood flow, what causes sepsis to occur? The villi of the small intestine contain many capillaries. Why are the capillaries so important? See all questions in Digestive System. Impact of this question views around the world.
In addition to the alimentary canal, the digestive system contains several accessory organs and glands. Hence this article discusses the difference between alimentary canal and digestive system.
Overview and Key Difference 2. What is Alimentary Canal 3. What is Digestive System 4. The alimentary canal is a long tubular canal starting from the buccal cavity or the mouth and ending at the anus. The gastrointestinal canal is a synonym of the alimentary canal. It is a continuous tube that has a length of 7. Smooth muscles form the alimentary canal.
Therefore, it is involuntary in nature. Throughout the tube, there are other accessory organs such as the pharynx, esophagus, stomach, small intestine, large intestine , rectum, and anus.
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