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In deuterostome development, which structure typically forms from the blastopore?
During gastrulation, an embryo's developing digestive tube initially forms as a?
What is a characteristic of indeterminate cleavage in deuterostome development?
What is the term for the process by which the blastopore forms the mouth in protostome development?
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What is the term for the formation of the coelom during embryonic development?
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What is the significance of identical twins in deuterostome development?
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What is the characteristic of bilateral symmetry in animals?
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What is the difference between protostome and deuterostome development?
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What is the significance of molecular data in understanding animal phylogeny?
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What is the characteristic of deuterostomy?
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What is the significance of blastopore fate in understanding animal phylogeny?
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What is the ancestral blastopore fate?
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What is the characteristic of cleavage in deuterostome development?
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In deuterostome development, what is the origin of the coelom?
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What is the fate of the blastopore in deuterostome development?
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What is the consequence of isolating a cell from a snail at the four-cell stage?
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What is the characteristic of the cleavage planes in deuterostome development?
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What is the result of the radial cleavage pattern in deuterostome development?
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What is a common characteristic of animal tissues that allows for flexibility and movement?
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Which type of reproduction produces genetically identical offspring in animals?
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What is the primary function of connective tissue in animals?
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Which type of feeding strategy involves feeding on waste products of other organisms?
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What is the result of the union of a sperm and an egg in animal reproduction?
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During embryonic development, what is the process by which cells migrate inward to form a second layer?
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What is the term used to describe the process of cell migration inward to form a second layer of cells during embryonic development?
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What is the term used to describe animals that lack a coelom?
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What is the term used to describe the layer of cells that forms the lining of the digestive cavity?
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What is the term used to describe the space that forms from the mesoderm in higher animals?
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Which group of animals has two germ layers: ectoderm and endoderm?
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What is the term used to describe the process of formation of a second layer of embryonic tissue called the endoderm?
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What is the characteristic of protostome development where cells divide in a spiral pattern?
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What is the term used to describe the formation of the coelom in true coelomates?
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What is the characteristic of deuterostome development where the blastopore develops into the anus?
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What is the characteristic of true coelomates that form the mouth first during embryonic development?
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What is the characteristic of true coelomates that have a cavity completely surrounded by mesoderm cells?
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What is the term used to describe the process of cell migration inward to form a second layer of cells during embryonic development?
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What is the characteristic feature of animals that belong to the clade Bilateria?
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Which group of animals is considered the basal group and sister taxa to the rest of the animals?
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What is the characteristic feature of deuterostome development?
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What is the characteristic feature of protostome development?
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What is the characteristic feature of the molecular phylogenetic tree?
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What is the characteristic feature of animals that belong to the group Ecdysozoa?
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Study Notes
Characteristics of Animals
- Animals are heterotrophs, acquiring energy through consuming food, unlike plants that produce energy through photosynthesis
- This characteristic is used to classify animals based on their feeding strategies
Feeding Strategies
- Herbivores: feed on plant material (producers)
- Carnivores: feed on consumers of plants
- Decomposers: feed on waste products of other organisms
- Parasites: feed on other organisms without killing them immediately
Tissues in Animals
- Muscular tissue: unique to animals
- Nervous tissue: unique to animals
- Connective tissue: provides structural support and protection
- Epithelial tissue: lines the outside and inside of the body, including cavities and organs
Characteristics of Animal Tissues
- Cells lack cell walls, allowing for flexibility and movement in animals
- Support for animal cells and tissues comes from specialized forms of tissues like bone, cartilage, and tough forms of skin
Reproduction in Animals
- Asexual reproduction: produces genetically identical offspring (e.g., budding, fragmentation in sponges, cnidarians)
- Sexual reproduction: requires sex cells (sperm and egg) and produces genetically diverse offspring
- Fertilization: the union of sperm and egg resulting in a zygote
Embryonic Development
- Zygote divides into multiple cells through reduction divisions, without cell growth
- Cells form a sphere-shaped structure called a blastula, which is hollow and filled with fluid
- Gastrulation: cells migrate inward to form a second layer, resulting in the formation of ectoderm and endoderm layers
- Development may continue to form a gastrula with three layers, used as a criterion for animal classification
Embryonic Development of Animals
- Blastula is a hollow sphere of cells filled with fluid (blastocoel) that forms during the embryonic development of animals.
- Cells migrate inside the blastula to form a second layer of embryonic tissue called the endoderm.
- The endoderm layer leads to the development of a gastrovascular cavity in animals like cnidarians (jellyfish, corals, anemones).
Germ Layers
- Sponges have no germ layers and no true tissues.
- Cnidarians have two germ layers: ectoderm (outside) and endoderm (inside).
- Flatworms (Platyhelminthes) and higher animals have three germ layers: ectoderm, endoderm, and mesoderm (in between).
- The presence of two or three germ layers is used in classification, with diploblastic animals having two layers and triploblastic animals having three layers.
Coelom and Cavities
- The mesoderm layer forms a space or coelom in higher animals.
- The coelom can be fully developed (true coelom) or partially developed (false coelom or pseudo-coelom).
- Examples of true coelom include mollusks, arthropods, echinoderms, and chordates.
- Examples of false coelom or pseudo-coelom include nematodes and Roryphians.
- The coelom gives rise to internal cavities, such as thoracic and abdominal cavities in humans, where organs develop and function.
- Animals without a coelom are referred to as acoelomates, such as flatworms (Platyhelminthes).
Classification
- Cnidarians are classified as diploblastic, having two germ layers.
- Flatworms are classified as triploblastic, having three germ layers, but are acoelomate.
- Higher animals are classified as triploblastic, having three germ layers, and may have a true coelom or pseudo-coelom.
Germ Layers and Developmental Trends
- Animals with three germ layers (ectoderm, endoderm, and mesoderm) are classified into three groups: true coelomates, pseudo-coelomates, and acoelomates.
True Coelomates (Eutelomates)
- True coelomates have a true coelom, a cavity completely surrounded by mesoderm cells.
- True coelomates are subdivided into protostomes and deuterostomes.
Protostomes
- Protostomes are true coelomates that form the mouth first during embryonic development.
- Characteristics of protostomes include:
- Spiral cleavage, where cells divide in a spiral pattern.
- Coelom formation by splitting from the blastopore, also known as schizo-coelom formation.
- Terminate development, where the removal of a cell from an embryo terminates its development.
Deuterostomes
- Deuterostomes are true coelomates that form the anus first during embryonic development, and the mouth forms later.
- Characteristics of deuterostomes include:
- Radial cleavage, where cells divide in a radial pattern.
- Coelom formation from outpockets of the primitive gut, also known as enterocoelom formation.
- Indeterminate development, where the removal of a cell from an embryo does not terminate its development.
Morphological Classification and Phylogenetic Trees
- Morphological classification of animals focuses on forms recognizable in adults and throughout development, including embryonic development.
- Phylogenetic trees are rooted trees that identify the hypothesized ancestor to all animals, which is a colonial kawano flagellate.
Early Animal Evolution
- The earliest animals are metazoans, which are multi-cellular organisms.
- The phylum Porifera (sponges) is considered the basal group and is sister taxa to the rest of the animals.
Body Plans and Symmetry
- Animals with true tissues belong to the clade Bilateria, which refers to bilateral symmetry.
- Cnidarians (jellyfish, anemones) and comb jellies have radial symmetry and do not belong to Bilateria.
Developmental Trends
- Deuterostomes are characterized by radial cleavage, formation of the coelom from pockets in the gut, and a primitive gut (archenteron).
- Protostomes are characterized by a blastopore that becomes the mouth.
- In deuterostomes, the mouth forms second, while in protostomes, the mouth forms first.
Molecular Phylogenetic Tree
- The molecular phylogenetic tree is based on molecular differences, such as genes controlling embryonic development.
- The tree is divided into two main groups: Deuterostomia and Protostomia.
- Deuterostomia includes animals such as vertebrates and some invertebrates.
- Protostomia is divided into two subdivisions: Lophotrochozoa and Ecdysozoa.
- Lophotrochozoa includes animals characterized by a feeding structure called a trochophore larva and a larval stage called the trocophore.
- Lophotrochozoa includes animals such as mollusks, annelids, and platyhelminthes.
- Ecdysozoa includes animals characterized by the process of ecdysis, where they molt their exoskeleton to grow.
- Ecdysozoa includes animals such as nematodes, arthropods, and tardigrades.
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Description
Learn about the characteristics of deuterostome development, including indeterminate cleavage, and its significance in the formation of identical twins and embryonic development.
