What is the classification for animals with full tube digestive tracts?

What is the classification for animals with full tube digestive tracts?

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What is the formal name for animals with full digestive tracts, by which I mean a mouth and an anus, and what is the classification for animals that have a single hole for exchanging food and waste?

Animals with a single hole do not form a monophyletic group: metazoa > eumetazoa >bilateria almost all have separate mouth and anus (except notably flatworms which is one reason it does not form a monophyletic group).

As species are not grouped in monophyletic groups by what they don't have (eg. invertebrates do not form a monophyletic group while vertebrates do) there is no particular group. Eumetazoa before the bilateria have a single mouth-anus.

Digestive System of an Earthworm

As a biology student, one needs to know about the earthworm's digestive system. If you are searching for some information on the same, to help you with your science homework, this article on earthworm digestive system would be helpful.

As a biology student, one needs to know about the earthworm’s digestive system. If you are searching for some information on the same, to help you with your science homework, this article on earthworm digestive system would be helpful.

The animal kingdom is broadly classified into two groups: non chordates (invertebrates) and chordates. Those animals that do not have a spinal cord or vertebral column are termed as non chordates, and those with a backbone on the dorsal side of the body are called chordates.

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Earthworms are examples of non chordates, that live within burrows of composting, moist soil. Pheretima posthuma, the common species of earthworms, is usually given to kids for their biology experiments while studying the anatomy of an earthworm.

Characteristics of Protists

There are over 100,000 described living species of protists, and it is unclear how many undescribed species may exist. Since many protists live in symbiotic relationships with other organisms and these relationships are often species specific, there is a huge potential for undescribed protist diversity that matches the diversity of the hosts. As the catchall term for eukaryotic organisms that are not animals, plants, fungi, or any single phylogenetically related group, it is not surprising that few characteristics are common to all protists.

Nearly all protists exist in some type of aquatic environment, including freshwater and marine environments, damp soil, and even snow. Several protist species are parasites that infect animals or plants. A parasite is an organism that lives on or in another organism and feeds on it, often without killing it. A few protist species live on dead organisms or their wastes, and contribute to their decay.

Phylum Chordata: Characteristics and Its Classification

The chordates were originated from a fish-like ancestor, very similar to the larva of the Ascidia (Tunicata) and it is assumed that they became the ancestor of the chordates by retaining the larval form throughout the life. In the palaeozoic age, the chordates were originated from some sessile Echinoderms, which were bottom dwellers of the sea. The primitive chordates resemble the non-chordates in some respects and are known as protochordates or invertebrate chordates. In the evolutionary course, They acquired new novelties and became vertebrates that were radiated on all ecological niches and became strong rivals of the non-chordates in the course of time.

The phylum chordata is a very diverse phylum which contains about 43,000 living species. Among them, most organisms belong to the subphylum, Vertebrata. This phylum is considered as the third largest phylum in the animal kingdom.

Characteristics of Phylum Chordata

At different stages in their life, chordates show the following four features. They are:

  1. Presence of the notochord
  2. Presence of the dorsal tubular nerve cord
  3. Presence of the paired pharyngeal gill-slits.
  4. Presence of the Post-anal tail.

Notochord: It is an elastic, rod-like longitudinal structure that is made up of cartilage. It is situated immediately above the alimentary canal (digestive tract) and just below the dorsal tubular nerve cord. The notochord is formed of special type of vacuolated cells and remains covered by a sheath, known as notochordal sheath. In the invertebrate chordates (urochordata and cephalochordada), it is formed of endothermal cells, but in the case of the vertebrate-chordates, it persists in the adult (with some exception), but in vertebrates, notochord is either partially, or wholly replaced by vertebral column. The main function of notochord is to support nerve cord.

Dorsal tubular nerve cord: It is a single hollow nerve cord which consists of bundle of nerve fibers that exists dorsally along the antero-posterior axis of the body, just above the notochord. Embryologically, this nerve cord originates from the dorsal ectoderm. It connects the brain to the muscles and other organs.

Paired Pharyngeal gill-slits: A pair of openings which connect the mouth and the throat, known as Pharyngeal gill-slits. At some stages of the life, all chordates possess paired pharyngeal gill-slits. In the primary aquatic animals, these remain persist in the adult and functions as the passage for the respiratory water current through the mouth, without entering the digestive system. The transition from aquatic to the land life involves pulmonary respiration and consequently the gill-slits lose their function. However, the initial stage of their formation is clearly observed in the embryos of the terrestrial chordates. In the adults, however, these are totally obliterated and become transformed into other organs like endocrine system.

Post-anal tail: It is an extension of the body away from the anus. Some chordates bear the tail with skeletal muscles, which assist in locomotion.

The digestive system of the horse

The horse's digestive system consists of those organs concerned with digestion, or the turning of complex food material such as hay, grass and corn etc, into simple substances such as carbohydrate, protein (amino acids), fatty acids, etc, which can be used by the body for energy, storage or body building processes. The organs consist of alimentary tract which is the tube extending from the mouth to the anus and know also as the gut, intestines or aliamentary canal, and the accessory organs such as the teeth, tongue, salivary glands, liver and pancreas.

The special characteristics of the horse's mouth are highly prehensile lips for gathering food which work in conjunction with the sharp front teeth when cropping grass, and the labile tongue which conveys the food to the back teeth. These have table-like surfaces crossed by ridges that form an ideal grinding surface between the upper and lower jaws.

Ducts which discharge digestive juices from the parotid mandibular and sublingual salivary glands open into the mouth. The roof of the mouth is formed by the hard palate in front, which continues into the soft palate behind. The soft palate forms part of the pharynx where the air passages and digestive tract cross one another.

As a horse swallows, the food crosses the pharynx and enters the gullet or oesophagus, from where it is conveyed to the stomach and thence to the small intestines, large colon, small colon and rectum.

The alimentary tract, from the stomach to the rectum, together with the pancreas and liver (glands which contribute more digestive juices and bile) are contained in the abdominal cavity. This can be described as a large `box', the sides of which are the diaphragm in front, the muscles below the spine forming the top, and the muscles of the.

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Animal Diversity Web

The annelids include earthworms, polychaete worms, and leeches. All members of the group are to some extent segmented, in other words, made up of segments that are formed by subdivisions that partially transect the body cavity. Segmentation is also called metamerism. Segments each contain elements of such body systems as circulatory, nervous, and excretory tracts. Metamerism increases the efficiency of body movement by allowing the effect of muscle contraction to be extremely localized, and it makes possible the development of greater complexity in general body organization.

Besides being segmented, the body wall of annelids is characterized by being made up of both circular and longitudinal muscle fibers surrounded by a moist, acellular cuticle that is secreted by an epidermal epithelium. All annelids except leeches also have chitonous hair-like structures, called setae, projecting from their cuticle. Sometimes the setae are located on paddle-like appendages called parapodia.

Annelids are schizocoelous and with a large and well-developed true coelom (i.e., one that is lined with mesoderm). Except in leeches, the coelom is partially subdivided by septa. Hydrostatic pressure is maintained across segments and helps maintain body rigidity, allowing muscle contractions to bend the body without collapsing it.

The internal organs of annelids are well developed. They include a closed, segmentally-arranged circulatory system. The digestive system is a complete tube with mouth and anus. Gases are exchanged through the skin, or sometimes through specialized gills or modified parapodia. Each segment typically contains a pair of nephridia. The nervous system includes a pair of cephalic ganglia attached to double nerve cords that run the length of the animal along the ventral body wall, with ganglia and branches in each segment. Annelids have some combination of tactile organs, chemoreceptors, balance receptors, and photoreceptors some forms have fairly well developed eyes, including lenses.

Annelids may be monoecious or dioecious. Larva may or may not be present if present they are of the trochophore type. Some forms also reproduce asexually. They are protostomes, with spiral cleavage.

Members of the Phylum Annelida can be found throughout the world, in marine, freshwater, and terrestrial environments. Ecologically, they range from passive filter feeders to voracious and active predators.

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A minimum of 30 credit hours, including 18 hours of graduate level course work in the degree program, is required. Students also complete and defend a thesis based on their research. The minor is optional. If a student selects a minor, the advisory committee must include a member from the minor field.

Digestive Phases

The response to food begins even before food enters the mouth. The first phase of ingestion, called the cephalic phase , is controlled by the neural response to the stimulus provided by food. All aspects—such as sight, sense, and smell—trigger the neural responses resulting in salivation and secretion of gastric juices. The gastric and salivary secretion in the cephalic phase can also take place due to the thought of food. Right now, if you think about a piece of chocolate or a crispy potato chip, the increase in salivation is a cephalic phase response to the thought. The central nervous system prepares the stomach to receive food.

The gastric phase begins once the food arrives in the stomach. It builds on the stimulation provided during the cephalic phase. Gastric acids and enzymes process the ingested materials. The gastric phase is stimulated by (1) distension of the stomach, (2) a decrease in the pH of the gastric contents, and (3) the presence of undigested material. This phase consists of local, hormonal, and neural responses. These responses stimulate secretions and powerful contractions.

The intestinal phase begins when chyme enters the small intestine triggering digestive secretions. This phase controls the rate of gastric emptying. In addition to gastrin emptying, when chyme enters the small intestine, it triggers other hormonal and neural events that coordinate the activities of the intestinal tract, pancreas, liver, and gallbladder.

Characteristics of Vertebrates

Vertebrata is a subphlyum of Chordata that is further defined by their bony backbone.

Learning Objectives

Identify the defining characteristics of vertebrates

Key Takeaways

Key Points

  • As chordates, vertebrates have the same common features: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.
  • Vertebrates are further differentiated from chordates by their vertebral column, which forms when their notochord develops into the column of bony vertebrae separated by discs.
  • Vertebrates are the only chordates that have a brain as part of their central nervous system.

Key Terms

  • vertebral column: the series of vertebrae that protect the spinal cord the spinal column
  • chordate: a member of the phylum Chordata numerous animals having a notochord at some stage of their development in vertebrates this develops into the spine
  • notochord: a flexible rodlike structure that forms the main support of the body in the lowest chordates a primitive spine

Characteristics of Vertebrates

Vertebrates are members of the subphylum Vertebrata, under the phylum Chordata and under the kingdom Animalia. Animals that possess bilateral symmetry can be divided into two groups, protostomes and deuterostomes, based on their patterns of embryonic development. The deuterostomes, whose name translates as “second mouth,” consist of two phyla: Chordata and Echinodermata. Echinoderms are invertebrate marine animals that have pentaradial symmetry and a spiny body covering the phylum includes sea stars, sea urchins, and sea cucumbers. The phylum Chordata contains two groups of invertebrate chordates, but the most conspicuous and familiar members of Chordata are the vertebrates.

Phylum chordata: All chordates are deuterostomes, possessing a notochord. Vertebrates are differentiated by having a vertebral column.

As chordates, all vertebrates have a similar anatomy and morphology with the same qualifying characteristics: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. However, the subphylum Vertebrata is distinguished from the phylum Chordata by the development of the notochord into a bony backbone. Vertebrates include the amphibians, reptiles, mammals, and birds, as well as the jawless fishes, bony fishes, sharks, and rays.

Diversity of vertebrates: animals with backbones: The subphylum Vertebrata contains all animals that possess backbones, gills, and a central nervous system in at least one phase of development. Vertebrates include amphibians, reptiles, mammals, and birds, as well as the jawless fishes, bony fishes, sharks, and rays.

More than 64,000 species of vertebrates have been described, but the extant vertebrate species represent only a small portion of all the vertebrates that have existed. Vertebrates range in size from the frog species Paedophryne amauensis (as small as 7.7 mm (0.3 inch)) to the blue whale (as large as 33 m (110 ft)). Vertebrates comprise about 4 percent of all described animal species the remainder are invertebrates, which lack backbones.

Anatomy and Morphology

All vertebrates are built along the basic chordate body plan: a stiff rod running through the length of the animal (vertebral column), with a hollow tube of nervous tissue (the spinal cord) above it and the gastrointestinal tract below. In all vertebrates, there is a mouth at anterior end of the animal and an anus before the posterior end of the body. There is a tail posterior to the anus during at least one phase of the animal’s development.

The Vertebral Column

Vertebrates are defined by the presence of the vertebral column. In vertebrates, the notochord develops into the vertebral column or spine: a series of bony vertebrae each separated by mobile discs. These vertebrae are always found on the dorsal side of the animal. However, a few vertebrates have secondarily lost their vertebrae and, instead, retain the notochord into adulthood (e.g., the sturgeon fish).

Vertebral column: A fossilized skeleton of the dinosaur Diplodocus carnegii shows an extreme example of the backbone that characterizes vertebrates.

Central Nervous System

Vertebrates are also the only members of Chordata to possess a brain. In chordates, the central nervous system is based on a hollow nerve tube that runs dorsal to the notochord along the length of the animal. In vertebrates, the anterior end of the nerve tube expands and differentiates into three brain vesicles.

Vertebrate Classification

Vertebrates are the largest group of chordates, with more than 62,000 living species. Vertebrates are grouped based on anatomical and physiological traits. The traditional groups include Agnatha, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammalia.

Animals that possess jaws are known as gnathostomes, meaning “jawed mouth.” Gnathostomes include fishes and tetrapods (amphibians, reptiles, birds, and mammals). Tetrapods can be further divided into two groups: amphibians and amniotes. Amniotes are animals whose eggs are adapted for terrestrial living this group includes mammals, reptiles, and birds. Amniotic embryos, developing in either an externally-shelled egg or an egg carried by the female, are provided with a water-retaining environment and are protected by amniotic membranes.