Invertebrates are animals that lack a backbone and they make up over 95% of known animal species. Almost every habitat on Earth, "from the scalding water released by deep-sea 'black smoker' hydrothermal vents to the frozen ground of Antartica" is occupied by them" (Reece, 680). The evolution in these miscellaneous environments has produced a vast diversity of forms. They range from a species composed of a flat bilayer of cells to species with features such as tentacles covered with suction cups. "Invertebrates also show enormous variation in size, from microscopic organisms to organisms that can grow to 18 m long (1.5 times the length of a school bus)" (Reece, 680). .
The invertebrate diversity is rather large, each animal ranges from having 1 species to 1 million. Porifera's have 5,500 species and the animals in this phylum are popularly known as sponges. They are sessile animals that lack true tissues, therefore, they live as filter feeders and trap particles that pass through the internal channels of their body (Reece, 681). Nemertea's have a mere 900 species and they are also known as ribbon worms. They swim through water or burrow in sand and extend a unique proboscis to capture their prey. Similarly to flatworms, they lack a true coelom, a main body cavity. However, they have an alimentary canal and a closed circulatory system where the blood is contained in the vessels and is distance from fluid in the body cavity (Reece, 682). Arthropodas have 1 million species, the most out of all the others. A broad majority of known animal species such as insects, crustaceans, and arachnids are arthropods. They have a segmented exoskeleton along with jointed appendages (Reece, 683).
Materials and Methods.
Exercise 1 was an invertebrate scavenger hunt. Students were given a list of clues provided by the lab instructor. The provided specimens were used to find organisms that possess the characteristics.
