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60 Cards in this Set
- Front
- Back
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Describe the importance of the cambrian explosion.
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The cambrian explosion is when there was high than normal diversity of animal life. There was a lot of adaptation in a short amount of time. Fossils from this time period show that all extant (existent) phylla were present.
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When did the cambrian explosion occur?
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The cambrian explosion occur during a brief period of geological time around 530 MYA.
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What are 2 hypotheses for why the diversity during the cambrian explosion occurred?
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There were increased oxygen levels in the oceans due to protists and cyanobacteria. There was also the evolution of predation, including light and movement sensing organs and armor.
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What gene important for the body plan of animals and plants evolved during the cambrian explosion?
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During the cambrian explosion, the homeobox (Hox) developmental gene complex evolved.
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What is the burgess shale fauna and where is it located?
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The burgess shale fauna is a fossil field in Canadian Rockies of British Columbia.
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Why is the burgess shale fauna famous?
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The burgess shale fauna is famous for exceptional preservation of soft body parts in black shale. Soft body parts usually don't form fossils, because it more easily decomposes.
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When do the fossils in the burgess shale fauna date to?
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The fossils date to Middle Cambrian.
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What are Anomalocaris?
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It was found in the burgess shale fauna and is a member of an extinct genus. It has few fossils.
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What are Opabinia?
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It was found in the burgess shale fauna and there are at least 20 species. It may have used a proboscis to search for food. It had 5 eyes.
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What modern animal do Anomalocaris and Opabinia resemble?
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Anomalocaris and Opabinia both look like arthopods today.
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What are Marrella?
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Marrella are an arthropod and the most common fossil found in the burgess shale fauna.
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What are wiwaxia?
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It was found in the burgess shale fauna and is soft bodied and scale covered. It was 2 inches long max, 464 specimens known. It has bilateral symmetry.
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What are Hallucigenia?
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It was found in the burgess shale fauna. There were 109 specimens from one fossil bed. Up to 3 cm long. It had tubes for feet and spikes for protection.
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Why are Pikaia important?
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Pikaia may be an ancestral chordate.
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What is a notochord?
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Notochord becomes the vertebral column.
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For animals that don't go on to have vertebral columns, what does the notochord function as?
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The notochord functions as a long, strong structure that muscles can be attached to, so there's something to pull against for locomotion.
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Describe the Pikaia.
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There are 16 specimens from Burgess, but 60 known. May have swam like an eel. ~1.5 inches long. Had antennae for sensing environment.
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What are 5 things that define an animal?
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Animals are eukaryotic, hetertrophs, multicellular, have movement, and don't have cell walls.
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Describe the eukaryotic aspect of animals.
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There are no prokaryotic animals and they have true nuclei.
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Describe the heterotroph aspect of animals.
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They can't make their own food. They are herbivory, predation, parasitism.
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Describe the importance of the multicellular aspect of animals.
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Animals' multicellularity allowed for multiple tissues to evolve. It increased specialization and complexity.
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Describe the movement aspect of animals.
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Animals have independent movement, even if for some it's only when young.
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What type of phyletic group are animals?
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Animals are a monophyletic group.
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How many species of animals are there?
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There are between 10-50 million species of animals.
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What are most species of animals?
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Most species are arthropods, so most animals have exoskeletons.
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What animals are included as arthropods?
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Anthropods include insects, crustaceans, and arachnids.
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Which phyla do humans fall into?
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Humans are included in the chordata phylum.
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Which major phyla includes the smallest number of species?
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The smallest number of species are included in the phylum echinodermata.
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What are 4 features that define the body plan?
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1. number of embryonic tissue layers. 2. type of body symmetry and degree of cephalization. 3. presence or absence of a fluid-filled body cavity. 4. the earliest events of embryo development
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What is a highly cephalized animal?
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A highly cephalized animal has a distinct head with lots of sensory organs.
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What are tissues?
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Tissues are tightly integrated structural and functional units of cells. Tissues are a group of cells with similar function.
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What is an epithelium?
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Epithelium is a layer of tightly joined cells that covers the body surface.
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What are diploblasts?
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Diploblasts are animals whose embryos have 2 types of tissues or germ layers: ectoderm and endoderm.
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What are triploblasts?
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Triploblasts are animals whose embryos have 3 types of tissues: ectoderm, endoderm, and mesoderm.
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What are germ layers?
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Germ layers = tissues. Germ layers develop into distinct adult tissues and organs.
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What is a basic feature of a multicellular body?
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A basic feature of a multicellular body is the presence or absence of a plane of symmetry.
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What is radial symmetry?
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Animals with radial symmetry have multiple planes of symmetry.
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What is bilateral symmetry?
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Organisms with bilateral symmetry have a single plane of symmetry and face their environment in one direction. (ex: humans).
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What are the 3 types of body symmetry?
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Asymmetry, radial, and bilateral.
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What is an example of an animal with asymmetry?
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Sponges are animals that have no plane of symmetry
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What is an example of an animal with radial symmetry?
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Jellyfish are animals with multiple planes of symmetry.
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What is an example of an animal with bilateral symmetry?
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Lizards are animals that have a single plane of symmetry.
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What is a coelom?
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A coelom is an enclosed, fluid-filled body cavity.
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What are acoelomates?
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Acoelomates are triploblasts that don't have a coelom.
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What are coelomates?
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Coelomates are triploblasts that possess a coelom.
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How does a coelom form?
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The coelom forms from within the mesoderm and thus is lined on both sides with cells from the mesoderm.
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What does a coelom function as?
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The coelom creates a container for circulation of oxygen and nutrients. (In humans, etc. instead have complex circulatory system). Also acts as an efficient hydrostatic skeleton.
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What is a hydrostatic skeleton?
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The coelom acts as an efficient hydrostatic skeleton that allows soft-bodied animals to move even without fins or limbs.
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What is the difference between pseudocoelomates and coelomates in terms of mesoderm?
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Pseudocoelomates have an enclosed body cavity partially lined with mesoderm. Endoderm on other side of coelom.
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What is the difference between pseudocoelomates and coelomates in terms of evolution?
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Pseudocoelomates have evolved several times, while true coeloms have evolved just once. Some animals have lost a pseudocoelom, become acoelomates.
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What do the ectoderm, mesoderm, and endoderm become?
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The ectoderm becomes the skin and nervous system. The mesoderm becomes the muscles and organs. The endoderm becomes the gut.
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All coelomates have what symmetry and how many embryonic tissue layers? What are the exception?
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All coelomates are bilaterally symmetric and have 3 embryonic tissue layers. The exception are echinoderms: bilateral in juvenile, but not adults.
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What is the difference between protostomes and deuterostomes in terms of cleavage?
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Protostomes have spiral cleavage, where the daughter cells form on space between parent cells. This causes it to be denser. Deuterostomes have radial cleavage, where the daughter cells are directly on top of parent cells.
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What is the difference between protostomes and deuterostomes in terms of the fate of embryonic cells?
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Protostomes have determinate development, so that if a cell is excised (removed), development is arrested. Deterostomes have indeterminate development, so that when a cell is excised, 2 normal embryos are formed. This is how we get twins.
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What is the difference between protostomes and deuterostomes in terms of the fate of the blastopore?
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For protostomes, the blastopore becomes a mouth and keeps going to form an anus. For deterostomes, the blastopore becomes an anus and keeps going to form a mouth.
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What is the difference between protostomes and deuterostomes in terms of the formation of the coelom?
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For protostomes, a block of solid mesoderm splits to form a coelom. For deterostomes, mesoderm pockets pinch off of gut to form the coelom.
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What are 2 advantages to segmentation?
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Segmentation allows redundant organ systems. (ex: cut off tail & still lives) Segmentation allows for more efficient and flexible movement, each segment can move independently.
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What are the 2 types of appendates?
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Unjointed appendages are sac-like. Also jointed appendages.
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What does the evolution of limbs make possible?
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The evolution of limbs made highly controlled, rapid-movement possible.
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Crabs (arthopoda) have what type of limbs?
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Crabs (arthopoda) have jointed limbs.
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