Annelida

Nick and Zach

**Annelida (Earthworms, polychaetes, leeches)**

**Life Processes:** Annelida live in many different areas and the life processes of annelida is very diverse from one area to another. Aquatic annelida hatch into larvae while land annelida hatch into smaller versions of their adult form. The aquatic annelida must metamorphosize into its adult form while the land annelida simply grow. Some reproduce asexually by budding, fissure, or fragmentation. Although they usually have separate sexes and hermaphrodite annelida is not rare. The annelida on land only mate after a heavy rainfall when the air is moist enough for them, but many of them die from predators. A huge evolutionary advantage for annelida is the ability to regrow body segments. This allows for the animal to survive longer and protect itself from predators. The life of a basic annelida, in a nut shell, is find a home, get food, and hide from predators.

**Method of Acquiring Nutrition:**  ﻿ ﻿ The methods used by annelids to acquire nutrients are different according to each polychaetes. The structure of each polychaete conducts how they attain nutrients. Polychaetes that have a pharynx with or without jaws feed on large particulate matter. These polychaetes can either be herbivores or carnivores. Some other species that eat smaller particulate matter are usually filter feeders, surface-deposit feeders, or burrowers. The filter feeders capture anything that is floating with their tentacles. The surface-deposit feeders take in food through a pharynx with jaws. The burrowers do mainly the same thing as surface-deposit feeders do.

**Body Plan:** Annelida are bilaterally symmetrical meaning that they can only be cut one way to still be symmetrical. Their body is a true coelem. This means that they have a body that is completely lined with mesoderm tissue and fluid filled. This allows organs to grow and move more independently and helps to form more complex organisms. Annelida have a segmented body, which allows for the regrowth of segments if something happens to them. The land annelida move by contracting their oblique and some have help from appendages. Also, the outer body wall is covered in setae. Setae helps grip the soil and help keep a specific shape for land annelida and helps to **increase surface area** of appendages for help to swim better. They also have a membrane called a cuticle. This helps with the facilitated diffusion of water by allowing water in, but not out. Annelida have a complete digestive track from their mouth to their anus. In their circulatory system, their blood never stops moving. This helps because it allows blood to circulate and obtain nutrients constantly. There are also no open sinuses for blood to drain from such as a nose.

http://myclasses.naperville203.org/staff/NNHSBiology/KraftsonEco/Animal%20Kingdom%20%20Period%202%20Picture%20Library/Annelida/annelida.bmp

**Ecological Niche:** Annelids are split into three different classes: Oligochaetes, Hirundinees, and Polychaetes. The oligochaetes live underground in moist soil and only come to the surface if there is heavy rainfall. The Hirundines live near fresh water because they cannot store water well. The polychaetes live in the ocean where they filter feed for food. The roles of annelids are to mate and gather food. Leeches, which are hirundines, prey on any visitors that come near their habitat. In this way, they are parasites to any visitors that enter their environment. The main challenges of annelids are avoid predators such as birds and rodents.

**Presense of specialized Systems:** Yes, annelida have specialized tissues.

Annelida have a complete digestive system from mouth to anus. This system contains the pharynx, esophagus, gizzard, and intestines between the mouth and the anus. Steps of digestion: - when the muscles associated with the pharynx contract food particles are sucked into the mouth - the food enters the esophagus and then the crop which acts as a storage area - the food enters the gizzard where it is ground and mashed - the food enters the intestine where more digestion and absorption occur - the intestines end at the anus where the food is excreted
 * Digestive System**

Like humans, there are a couple main blood vessels, such as the dorsal and the ventral blood vessels. These branch off into littler blood vessels which supply the rest of the body with nutrients. These vessles branch off into capillaries where nutrient and possibly gas exchange occurs.
 * Circulatory System and Gas Exchange**
 * They have aortic arches that pump the blood rather than a heart***

Annelida have brains, even if they are very small which are connected to the main nerve cord, called the ventral nerve cord, by a ring of nerves. The ventral nerve cord runs the length of the body and provides nerves for each segment of the body. Sense organs include: Eyes Taste buds Tactile tentacles Statocysts (help in equilibrium)
 * Nervous system**

Some aquatic annelida have gills for respiration and gas exchange Most annelida respirate directly through their skin because they have no special organs for gas exchange
 * Respiratory System**

Annelida reproduce both sexually and asexually. Asexually is done by budding, fragmentation, or fission. Hermaphrodites are common among annelida that reproduce sexually. Eggs of aquatic annelida hatch and are larvae, then they must evolve into their adult form. The land annelida hatch from cocoons and are born straight into littler versions of their adult forms, so all they have to do is grow.
 * Reproductive System**

**Evolutionary History:** Annelids have adapted mainly to perfect their body structure. One adaptation is ability to replace any damaged or cut off body segments. They do this by spreading their organs and keeping a segment that is similar to the severed segment. They have also adapted to have a cuticle, which allows water to diffuse into their bodies. Another adaptation is that Annelid is always circulating and is never not used. The final adaptation is their ability to move on land by contracting their muscles. Some annelids are aided by appendages in order to move easier.

**Interesting Others...** []

http://scienceblogs.com/zooillogix/giant%20gippsland%20earthworm.jpg

http://araku.ac.ir/~museum/images/bio%20pic/Annelida.jpg

http://www.fcps.edu/islandcreekes/ecology/Miscellaneous/Freshwater%20Leech/Skin.jpeg

http://johnson.emcs.net/life/images/earthworm.jpg

http://yhsbiology.wikispaces.com/file/view/earthworm_structure/48568043/earthworm_structure

http://myclasses.naperville203.org/staff/NNHSBiology/KraftsonEco/Animal%20Kingdom%20%20Period%202%20Picture%20Library/Annelida/annelida.bmp

** Bibliography: **

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http://www.slideshare.net/guestd9437bf/phylum-presentation-annelida

http://www.ento.csiro.au/education/allies/annelida.html

http://www.britannica.com/EBchecked/topic/26308/annelid/31777/Food-and-feeding

http://www.factmonster.com/ce6/sci/A0856624.html

Ecology Homework Assignment #1 Abiotic vs. biotic components of the ecosystem or biome of Annelida - How are they connected?

Abiotic factors:
 *  Sunlight
 *  Rainfall
 *  D irt
 *  Temperature
 *  Freshwater
 *  Saltwater
 * Machines
 * Trash

Biotic Factors:
 * Other organisms (fish, algea, squirrels, mice)
 * Plants (trees, bushes, grass, algae)
 * Humans
 * Insects

Biome/Ecosystem Annelids live in two different biomes because of their eating adaptations. Some organisms such as earthworms live in forests while others such as leaches and polychaetes live in aquatic biomes. Forests are filled with arthropods and are full of trees, bushes, ferns, and rivers as well as dirt. Earthworms are known to be burrowers, which is why this is the perfect biome for them since they live underground and obtain nutrients from roots and the dirt. In aquatic biomes such as rivers and ponds, leeches live there because they cannot hold water in their bodies long. They need to live in moist biomes because it is necessary for their survival. Rivers and ponds are fresh water and have plants and animals living in the water while other plants and animals live along them.

Connection between Biotic and Abiotic Factors

The abiotic factors that determine the biome and ecosystem are the main factors. These include sunlight, rainfall, temperature, and dirt or type of water. By affecting the area that the annelids live in it also determines what biotic factors can live there. Squirrels, birds, and mice can't live under water and fish can't live above water. This is also true for plants. Certain plants can't grow in certain places. These affect annelids because is will affect what predator and prey there are in the environment. The diversity of plants will affect the food source from area to area. This will affect the survival rate, reproduction rate, and other life factors. Humans have a huge affect on annelids as well. We ourselves kill, capture and study annelids. Our trash and machines also take a toll on the annelid population.