DIVERSITY OF LIVING THINGS (INVERTEBRATE ANIMALS) G9 Alpha and Delta – 2011 Mr. ARNOLD, Rafael

Main Characteristics: They don’t have back bones; They can be found in many different environments; They can live in water or very dry land; They can live inside other organisms.

Most of them are small...

But some can be very large!

SPONGES

Characteristics: They’re the simplest multicellular animals on Earth; They’re sessile animals (attached to one spot); Most of them live in the ocean (a few in fresh water); They have no tissues or organs; They’re made up of a collection of cells organized into a body wall; They were adapted to feed continuously (plankton and other tiny animals).

Specialized Cells The cells are specialized for different functions; Pore cells create tiny openings throughout the body; Pores lead into larger canals containing cells with flagella (choanocytes), which move water through the sponge; Some cells filter out food and O 2, others digest the food; Most of them have spicles, which are made up of calcium and silicon (gives shape and provides support).

Asexual Reproduction Buds are formed alongside the parent sponge; Buds break off and float away; Finally the bud attaches to a surface and start growing. No Genetic Material Exchange!

Sexual Reproduction Sperm can be released into the water and meet eggs which were also released there or... Eggs can be in the body wall, so that the sperm enter the sponge and fertilize the eggs. A fertilized egg becomes a larva, which is able to swim and attach to another surface to develop.

Larvae of the sponge Amphimedon queenslandica Larva of the sponge Rhopaloeides odorabile

CNIDARIANS

Characteristics They are found only in water; The group includes Jellyfish, Corals, Sea Anemones and Hydras; They feed from plankton, fish and clams; They’re sessile for most of their lives. JellyfishCoralsAnemonesHydras

Cnidarians have tentacles with special stinging cells, which enable them to capture prey; Each stinging cell has a capsule named nematocyst, that holds a coiled filament and releases it when there’s physical contact.

Accidents with Jellyfish

Tissues and Body Systems Cnidarians are made up of flexible layers of tissue, which along the specialized cells made up the body systems; There’s a central opening where food is taken in and wastes are released; Sting cells are able to paralyze preys and also protect cnidarians from predators; Tentacles also take food to the opening which leads to a gut where it’s digested.

Central Opening – “mouth”

A simple muscle system for movement is present; When the muscle cells shorten (contract), they produce movement; A simple network of nerve cells is present all over the body.

Reproduction Reproduction can be sexual ou asexual; In asexual reproduction buds are carried away from the sessile parent by water.

In sexual reproduction sperm is carried to the egg and fertilization results in a free larva; Larva settles on the ocean floor and grows into a form called polyp, which is sessile and develops a pile of disk shaped buds; Once the buds are mature they are released and become a medusa, which is mobile.

Sexual Reproduction

WORMS

Characteritics Bodies may be simple or very well developed; Body is tube-shaped – bilateral symmetry; Most of the times food enters through the mouth, is processed in the digestive tract and leaves the body through the excretory organ; They take in the oxygen present in water through the skin (moist environments necessary!).

Segmented Worms Annelids Segmented Worms aka Annelids Bodies divided into individual segments;

The organs are organized into body systems; The digestive system is composed of digestive and storage organs, and is connected to the excretory system; Worms digest animal and plant matter from the soil and excrete what’s left over (fact that enriches the soil!).

They have several layers of muscle tissue in their body wall; Hairlike bristles help to anchor in the soil as it moves; The nervous system is composed by a brain and a nerve cord that runs through the body.

Segmented Worms Reproduction Reproduction can be sexually or assexually; There are no distinct male or female worms (they carry both reproductive structures); In order to reproduce two worms exchange sperm; –Sperm fertilizes eggs –Eggs are laid –Eggs hatch into larvae –Larvae develop into worms.

Flatworms They have the simplest bodies; Movement can be performed using cilia instead of muscles; Nutrient absorption is done through skin; Most of them are parasites (no need of digestive system once food is digested by the host).

Roundworms They’re found everywhere on Earth; Muscles, nervous and digestive system is present; Some of them are important decomposers and parasites.

MOLLUSKS All mollusks are soft-bodied animals; Many of them have an outer shell; They live on land, fresh and salt water; Mollusks are divided into 3 groups.

1. Bivalves They have a hard shell made up of two matching halves; When the shell is closed it completely encloses the body; There isn’t a distinct head, but a mouth and sensory organs are present.

Bivalves filter food from the water; To move they use a foot, which is also used for burrowing and digging; Oxygen intake is peformed by a pair of gills (it filters oxygen from water).

2. Gastropods It’s the most diverse group; Some live on land (e.g. slugs and snails) and others in water (e.g. conches and whelks); Gastropods withdraws in the shell for protection. Slugs SnailsConchPeriwinkle

Their head is located at the end of its foot; They have a pair of eyes and a pair of tentacles for sensing; Many of them have a cutting mouth part called radula; Some gastropods eat animals, but most feed on algae and plants; Water Gastropods  Gills Land Gastropods  Lungs

3. Cephalopods Cephalopods live in saltwater environments; They have the most well-developed body systems. NautilusOctopusSquid

A brain with very well-developed nerves is present; They have a pair of eyes close to their mouth; They have tentacles (arms) for capturing prey and also for taking food to their mouth; A structure called siphon produces a jet of water responsible for the cephalopod movements; Gills take in oxygen, which is pumped through the body by 3 hearts.

A dark color ink-like fluid is released in the water for protection. Octopus Releasing Ink – SC Coast, South Carolina

ECHINODERMS They are a group that live in the ocean and have radial symmetry; They feed off the ocean floor as they move along. Sea StarUrchinCucumberSand Dollar

Spines and Skeletons in Echinoderms Gk. Ekhinos = spiny / Gk derma = skin “Spiny-Skinned” More visible in Urchins, but present in all Echinoderms

They have no bone tissue, but a skeleton made up of Calcium is present

A mouth is located at the center of the body (underside); Urchins and Sand Dollars feed from their surroundings (filtering); Sea Stars are predators. Sea Star eating a shrimp.

Water Vascular System and Tube Feet The water vascular system is made up of tubes filled with water; Openings along the upper surface of the body feed water into this tube continuously.

ARTHROPODS

Most invertebrates are arthropods; Exoskeleton  Strong outer cover (chitin); Jointed legs  Great range of movements even with a ‘hard’ cover.

MOLTING The process of shedding the exoskeleton.

Complex body systems Nervous system with a brain and different sensory organs; Digestive system includes stomach and intestines; Heart pumps blood into the body directly – no blood vessels; Either a male or female reproductive body system (Sexual Reproduction).

General Morphology Earthlife.net

General Anatomy

INSECTS 3 pairs of legs; Most live on land;

Crustaceans Number of body segments and pairs of legs varies; 2 pairs of antennae; Most live in water (some on land)

Arachnids 4 pairs of legs and 2 body segments; No antennae; Most live on land.

Metamorphosis