Invertebrates Homework
Mollusks are soft bodied invertebrates that are typically have a muscular foot and a mantle that
might secrete a protective shell, and a visceral mass containing organs. They also possess a
radula known as feeding organ and a well-developed circulatory system. Mollusks also include a
diverse animal such as snails, clams, squids, and octopus. Annelids are segmented worms that
are characterized by a segmented body with repeating units. They have a very well-developed
coelom also known as a body cavity and exhibit bilateral symmetry. They possess a closed
circulatory system, a digestive system with a mouth and an anus, as well as a nervous system
consisting of a ventral nerve cord. Examples of the annelids include earthworms, leeches and
polychaete worms. Next, the arthropods which are a diverse group of invertebrates
characterized by a segmented body, jointed appendages, and exoskeleton made of chitin.
Arthropods exhibit bilateral symmetry and have a well-developed nervous system with sensory
organs. Arthropods have a specialized respiratory system, consisting of gills or tracheae.
Examples include insects, spiders, crustaceans, and millipedes. Echinoderms are characterized
by radial symmetry as adults and a spiny skin. Echinoderms possess a water vascular system,
which helps in locomotion and feeding and have a unique hydraulic system of tube feet.
Echinoderms also exhibit regenerative abilities. Some examples would be starfish, sea urchins,
and sea cucumbers. Lastly the invertebrate chordates, which are chordates that lack a vertebral
column also known as backbone. They also still possess chordates but some characteristics.
Which include a notochord, a dorsal nerve cord, pharyngeal slits, and post-anal tail. Some
examples include tunicates also known as sea squirts, and lancelets also known as amphioxus.