Quiz 25: Animal Evolutionthe Invertebrates


Coral reefs are the class of invertebrates that belongs to the phylum Cnidaria. These organisms have symbiotic association with algae namely zooxanthellae. Different reef areas support different coral species; wave energy is the most important determinant. Other major location determinants include temperature, light availability, sediment load, salinity, and exposure to air. Space and availability of sunlight are the primary limitations and resources for competition among corals. Hypothesis: An aquatic ecosystem, especially the marine ecosystem is most suitable for the growth of corals. The most crucial factors that affect the growth of reefs are: Temperature, and illumination of light. Here, the soft coral reef is growing in only facing toward the inland (one-sided distribution), because the edge of inland is more convenient to capture sunlight (specified range of illumination) for photosynthetic activity of zooxanthellae. So, if the zooxanthellae is survives, then coral reef also get enough food for their growth and reproduction. If the soft coral reef is growing in the deep water, then it might not get specified range of illumination for the photosynthetic activity of zooxanthellae. So, coral reef ecosystems are most diversified and productive systems, because of their symbiotic association with zooxanthellae and efficient nutrient utilization. Coral reef building occurs in a cycle of destruction, cementation, colonization, and then again to destruction. This mechanism is can study by following method. If we increase the temperature of water of coral reef ecosystem, then the zooxanthellae are detaches from the surface of corals. Thus, the growth of coral is inhibited.

Animals are able to reproduce asexually as well as sexually. But not all animals reproduce asexually as well as sexually. Hence, option (c) is incorrect.

Nautiloids are large and assorted gathering of marine cephalopods (Mollusca) having a place with the subclass Nautiloidea that started in the Late Cambrian and are spoken to today by the living Nautilus. Nautiloids prospered amid the early Paleozoic time, where they constituted the principle ruthless creatures, and created exceptional differing qualities of shell shapes and structures. Nearly 2,500 types of fossil nautiloids are known, yet just a hand sized scoop of species get by to the present day.

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