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Blastopore becomes the anus2/3/2024 In the other group, called Deuterostomes (meaning “mouth second”), the blastopore becomes the anus and the digestive tract stretches from hind to fore, eventually “punching” through the head region to form the mouth. The word Protostome means “mouth first.” Protostomes include a huge variety of animals such as insects, crustaceans, earthworms, mollusks, and most other “creepy-crawlies” you are familiar with. In one group called Protostomes, the blastopore becomes the mouth, and the gut tract develops until it “punctures” the other end of the animal, forming the anus. Yes, even we humans develop a blastopore as the beginning of our gut tract.Īmong the bilaterian animals, there has traditionally been a split proposed that divides these organisms into two groups based on a fundamental difference in the way their digestive tracts develop. That somewhere is a puckered indentation called a blastopore that forms early during their embryonic development. This involves the formation of a gut tube, and like all tubes it has to start somewhere. True or false: Nematocysts are the most complex structures secreted by single animal cells.You may not appreciate it, but one of the key developments of bilaterian animals is forming a distinct mouth and anus. They resemble a protist with a single flagellum. They can consume particles many times their size by stretching their cells. They circulate water with their beating flagella. ![]() They capture food particles from passing water. Select the statement that is not true concerning choanocytes. The blastula folds inward to form a hollow sac with an opening called a blastopore, a developmental stage called a gastrula. Zygotes undergo mitotic divisions called cleavage.Ĭleavage produces a ball of cells called a blastula. Zygotes are formed from the fusion of haploid gametes. Select the correct statement concerning embryonic development. Match the type of heterotroph with food source. The evolution of specialized tissues may be a key innovationĮvolution failed to develop a powerful innovation All other animals differentiate irreversibly. Sponge cells are able to dedifferentiate and then redifferentiate. ![]() Spiral cleavage humans blastopore becomes mouth Radial cleavage echinoderms blastopore becomes mouth Indeterminate development humans blastopore becomes anusĭeterminate development echinoderms blastopore become anus Select the correct set of attributes for deuterostomes. Mediated at the molecular level by Hox genesĪllows that damage to any one segment need not be fatal because other segments duplicate the damaged segment's functions. Select the correct statement concerning segmentation. Which of the following do Lophotrochozoa include? Protostomes that molt their cuticles at least once during their life With which of the following are arthropods now grouped? On the state of what did morphology-based phylogeny focus? Which of the following is characteristic of sponges? True or false: It is accepted that the animal kingdom is monophyletic. The annelids and arthropods are now moved into different clades, and the arthropods are now assigned to _, animals that molt. ![]() Recent molecular data has led to a revision of the traditional classification of animal phyla. How do sponges differ from all other animals?Ĭells can differentiate from one type to another Which of the following is a defining characteristic of an animal?Īll choices are defining characteristics. What innovation made possible the development of advanced organ systems?īody cavity isolated from the exterior of the animal Molecular data supported what had been the minority view that the phylum Porifera is monophyletic. It is comprised of 2 or 3 distantly related groups. What has recent molecular data revealed abut the phylum Porifera? Which of the following is NOT a key innovation in animal evolution?Įvolution of tissues, allowing specialized structures and functionsĮvolution of various patterns of embryonic developmentĪll choices are key innovations in animal evolution. Spiral cleavage/indeterminate development/blastopore forms anus/coelom from mesodermal split ![]() Spiral cleavage/determinate development/blastopore forms anus/coelom from mesodermal split Radial cleavage/determinate development/blastopore forms mouth/coelom from mesodermal split Spiral cleavage/determinate development/blastopore forms mouth/coelom from mesodermal split Radial cleavage/ indeterminate development/blastopore forms anus/coelom from invagination of archenteron Select the correct array of defining features for protostomes.
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