Describe the different classes of echinoderms using examples.

Echinoderms are divided into the five classes: Asteroidea (sea stars), Ophiuroidea ( brittle stars), Echinoidea ( sea urchins and sand dollars), Crinoidea( sea lillies or feather stars) and Holothuroidea( sea cucumbers)

Explanation:

The term Echinoderms is derived from the latin word Echinodermata ( name of the phylum)  that includes star fish and sea urchins from Greek ekhinos "sea urchin" originally "porcupine, hedgehog"(see echidna)+derma means skin so called from its spiky shell.

Charactersitic features of Echinoderms:

Echinoderms don't have brain they have nerves running from mouth into each arm or along the body.They have a shell made up of calcium carbonate which is covered by skin.They get their food and oxygen for energy. They use tube feet to obtain from water.The tiny tube feet are involved in passing collected food towards the central mouth. These animals are detritivores performing similar functions to earthworms on earth  on land in recycling nutrients.

There are five classes of echinoderms:

Asteroidea (sea stars), Ophiuroidea ( brittle stars), Echinoidea ( sea urchins and sand dollars), Crinoidea( sea lillies or feather stars) and Holothuroidea( sea cucumbers)

americans began to notice growing differences between the northern and southern sections of the country. there were more people living in cities in the north, which made it more urban. more people lived on farms in the south, which made it more rural. while many people were farmers in the northern states, there were now other ways to make a living, such as working in mechanical cotton gins factories manufacturing cloth, tools and other goods. people in the north supported high tariffs on goods imported from europe because the extra cost encouraged people to “buy american” instead. in the southern states, planters did not like tariffs because they sold most of their production to europe and bought their tools from there as well. southerners believed the protective tariff was something that only northern factory owners keep their profits high. so the southern politicians came up with an idea. they would opt out. they would simply ignore the protective tariff. it was ‘null and void’ in south carolina. the state would not collect the taxes on goods imported into south carolina, no matter what the president said they had to do. this decision led to the nullification crisis.

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answer: collecting information/data

reason: the student is going around and asking people questions to collect data

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