Focus 11: Phylum Annelida

Give a few examples of animals found within this taxon.

earthworms, clam worms, tube worms

How many species are found within the phylum Annelida? During which time period did the phylum originate (according to the fossil record)?

22,000 spp and originated 600 mya according to fossil records

The film emphasized a major contribution of the phylum Annelida in relation to global temperatures. Explain!

thought activity of annelids was responsible for global warming and allowed life to move to land. Annelids were the first to burrow and the burrowing activity tapped into organic matter buildup which other organisms couldnt access and annelids ended up releasing a shit ton of CO2 which warmed up the atmosphere

Briefly characterize the phylum Annelida.

segmented roundworms, protostomes (means they formed mouth first rather then anus first), bilateral symmetry, complete gut, ventral nerve cord, cephalization (brains get bigger and more condensed as movement increases)

What are the "new" evolutionary features of the phylum?

New features include metamerism which is segmentation and also the coelom which is the body cavity and setae are bristles/hairs, metanephridia which are kidney like structures found in each segment.

What is metamerism? What is the importance of metamerism?

metamerism is segmentation and its important because it allows different segments to move separately and also allows for more complex/specialized systems of organization. In annelids each segment can be separated by each setae

What are setae? What is their importance?

A setae is the bristles found on the sides of the annelids that aids the worm in movement and plays some role in sensing the environment

Give a brief overview of the classification within this phylum.

Class Oligochaeta, Class Polychaeta, Class Hirudinea

Characterize the class Oligochaeta.

known as the few haired ones, there are 10,000 spp and include earthworms and their relatives and they can live in a variety of environments including freshwater and on land

What is the ecological importance of earthworms?

earthworms make the soil fluffy which allows for gas exchange for plants and other organisms in the earth and castings also fertilize the soil and recycle bio matter by draggin the nutrients into the soil

Explain how earthworms move (use their anatomy as a foundation to explain their movement pattern).

earthworm each segment can contract and expand and use setae to like anchor and move

Make a drawing of the anatomy of an earthworm and label important structures. Do you know the function of each of these structures?

What is a typhlosole?

a typhlosole is a fold in the intestine which is to increase surface area

Give a brief overview of the anatomy of the digestive system in an earthworm. How does it differ from a Nematode worm? From a flatworm? What kind of changes have occurred in the digestive system? Is it more efficient? If so, explain why?

more differentiation, earthworm has differentiation in the tube it has different lumps of different things instead of a straight tube ie crop and gizzard and stuff

What is the importance of the circular and longitudinal muscles in each of the segments of an earthworm?

better movement. Circular muscles make worm skinny, longitudinal muscles make them shorter

Briefly describe the circulatory system in an earthworm (including hearts and the location of the major blood vessels).

dorsal and ventral blood vessels with 5 aortic arches

How does an earthworm exchange gases with its surrounding environment?

diffusion over epidermis

How do earthworms reproduce?

they put themselves in each others clitellum

Give a brief overview of the anatomy of the reproductive system in these animals.

Hermaphrodites; each has a reproductive system with seminal vesicles, seminal receptacles, an ovary, and an oviduct. They mutually exchange sperm to mate.

Briefly describe the nervous system of an earthworm.

A ventral nerve cord, nerves penetrating tissues, and a brain made of fused ganglia

How do these animals excrete waste products?

through the anus and nephridia with pores to the outside

Characterize the class Polychaeta.

10k sp described, most free living and nocturnal, lots live in meiofauna realm

How does a polychaete worm differ from an oligochaete worm?

bigger setae, many have parapodia, different feeding mechanisms (not just substrate)

What is meiofauna? What kind of animals are components of the meiofauna?

the realm between grains of sand, worms like nematodes and annelids live here, as well as really tiny crustaceans

What is a parapodium? What kinds of functions can one attribute to the parapodia in this class of worms?

A parapodium is a paddle-like appendage with the setae on it that aids the worm in movement and sensation

What is the difference between raptorial, deposit and filter/suspension feeders?

raptoral: capture prey or herbivory

-direct deposit feeders: feed directly on sand / mud

-selective deposit feeders: tentacles spread out over sediment and selectively capture particles to draw into mouth

-filter/suspension feeders: filter through falling particles in water current

Elaborate on the anatomical structures polychaete worms use to "capture" food with each of these three feeding strategies.

Deposit feeders use cilia and their tentacles to grab food

Filter feeders use their systems to pump water through their body and feed off the particles that flow through them

Predators use their cilia and mucus to trap their prey

What is the advantage of tube building in these animals?

the advantage of tube building is its good protections and easy to hide in

What kind of evolutionary advantages are associated with burrowing?

The advantages are they are protected from predators above ground and have access to a lot of nutrients which was inside the soil

How do burrowing worms access nutrients? How do they do gas exchange?

Through the use of diffusions the worms can access the nutrients. How they do gas exchange. Usually there is a current inside their tunnel which is constructed in a certain way to allow for gas exchange

What is a "spaghetti" worm (terebellids)? Briefly describe the lifestyle of these worms.

Spaghetti worms are a type of marine burrowing worm that live on the ocean floor. They use their tentacles that stick out of their burrow to catch food. They mostly stretch out their tentacles to get tiny particles of food in the water. Technically they are filter feeders.

How do "feather duster" and "christmas tree" worms capture food? Perform gas exchange?

They use their feathers like parapodia to filter food out. Also use them for breathing via diffusion.

What is epitoky?

epitoky is the process in which sexually inactive worms become sexually active and mature and move a lot to increase chances of reproduction

Briefly describe the "class" Hirudinea.

"class" hirudinea are true leeches part of the annelida family that are different from other annelids due to the presence of an anterior and posterior sucker

Are leeches really a member of the phylum Annelida? Describe the Annelid feature/s of a leech.

they are segmented they have complete gut and they have bilateral symmetry

Why do leeches suck blood? Briefly explain how leeches are able to gain access to blood from a host?

leeches suck blood because it's nutritious and basically they inject you with anaesthetic and then stick to your body and drink blood with its mouth until it has its fill using its suckers.

Describe the anatomy of a leech? How is the anatomy of a leech correlated to its feeding behavior?

Leeches have a long segmented soft body with suckers on both ends which correlates with its feeding behavior which is to gorge itself until it can't anymore on blood and the suckers and the anaesthetic they inject before feeding help with that.

What is the importance of leeches in human medicine (past and present)?

leeches are important because in the past they were believed to heal diseases by sucking out bad blood. Today leeches have compounds called anticoagulants that are used after surgery to prevent blood from clogging.

Briefly summarize the characteristics of the phylum Annelida as well as the major attributes of the classes within the phylum.

Annelids are segmented, bilaterally symmetrical, coelomate invertebrates with a closed circulatory system, a complete digestive tract, and a nervous system, and are divided into classes like Polychaeta, Oligochaeta, and Hirudinea.