ZOOL 110 exam 2 Annelida & Ecdysozoans

What are the defining features of Clade Clitellata, what classes does it inculde?

the presence of a clitellum, have few setae. Includes class Hirudinia and the non-monophyletic group Oligochaetes

What are the defining features of Clade Errantia (motile polychaetes)

many are euryhaline, parapodia on each segment, have many setae, and a well-defined head with sense organs

What is the structure of the annelid circulatory system?

Annelids have a closed circulatory system, gas exchange occurs though gills, skin, or parapodia

How does the annelid excretory system function?

Annelids have a complete gut with paired nephridia

What are the main features of the annelid nervous system?

Annelids have a double ventral nerve cord with paired ganglia in each segment

How do leeches (Class Hirudinea) feed?

Leeches have anterior and posterior suckers that allow them to attach to hosts. They are carnivorous and can be temporary or permanent parasites. They are fluid feeders; their salivary glands secrete anesthetic to numb the host and anticoagulants to prevent blood clotting, allowing them to feed on the blood without the host noticing.

What are the features of Sipuncula?

Sipunculans (peanut worms) have an introvert for feeding and a trunk

In the context of body plan evolution, what “first” do we see in annelids?

Segmented body plan

How does a hydrostatic skeleton work?

muscles contract against fluid rather then bone, works like an elephant trunk

How do earthworms reproduce?

Earthworms have a clitellum that secretes a viscid sac that eggs are deposited in. They are monecious

What is a velvet worm? How do they feed?

Velvet worms (Onychophora) are Ecdysozoans with an open circulatory system. They are small and caterpillar-like. They feed by secreting a sticky substance to immobilize prey.

What is a tardigrade? Why are terrestrial tardigrades so amazing?

Tardigrades are Ecdysozoans with an open circulatory system. They are known for being incredible survivors

What puts the onychophorans and the tardigrades in the group Ecdysozoa?

They go through ecdysis, the molting of the cuticle