Table of Contents
Are cephalopods annelids?
Structure and Function of Annelids. Annelids have other similarities with mollusks, including: A closed circulatory system (like cephalopods). An excretory system consisting of tubular nephridia.
What phylum is octopus?
Clams, Snails, and Squid: Phylum Mollusca, Class Cephalopoda. Cephalopods are a group of molluscs that include the pearly chambered Nautilus, squids, and the octopus.
What is the difference between mollusks and annelids?
Most mollusks have shells. Annelids are worms such as the familiar earthworm. They have segmented bodies. Annelids look like roundworms on the outside, but on the inside they are more like mollusks.
Is an octopus a cnidaria?
Because of the different anatomy and physiology of these two organisms, they are categorized under different phyla. Octopus is categorized under Phylum Mollusca while Jellyfish is categorized under Phylum Cnidaria.
Are annelids amphibians?
Worms are neither insects nor amphibians; they are annelids.
What kind of mollusks are in the annelid group?
The annelids traditionally include the oligochaetes, which include the earthworms and leeches, the polychaetes, which are a marine group, and two other smaller classes.
How many species of annelids are there in the world?
The coelom is reduced in leeches, and setae are lacking a few specialized forms, including leeches. A major invertebrate phylum of the animal kingdom, the annelids number more than 9,000 species distributed among three classes: the marine worms (Polychaeta), which are divided into free-moving and sedentary, or tube-dwelling,…
What kind of body plan does an annelid have?
The phylum includes earthworms, polychaete worms, and leeches. Like mollusks, annelids exhibit protostomic development. Annelids are bilaterally symmetrical and have a worm-like appearance. Their particular segmented body plan results in repetition of internal and external features in each body segment. This type of body plan is called metamerism.
What kind of cells does an octopus have?
Their skin contains cells called chromatophores that allow the octopus to change color and pattern. They are believed to be quite intelligent—capable of learning, using tools, and remembering locations. There is tremendous range in the size of octopus species found in U.S. waters.