What are they? Invertebrate Animals

Invertebrates Animals that do not have a backbone or any bone tissue. Most are limited in size because of support. Ocean-dwelling can grow larger.

Sponges: Phylum Porifera Simplest multicellular animals on Earth. Sessile: they are attached to one spot and do not move. Most in ocean, some freshwater. Body is a collection of cells organized into a body wall. Feed on plankton and tiny organisms in water.

Sponges: Phylum Porifera

Specialized Cells Pore cells- small openings in body, lead to larger canals. The canals open into central space, where small cells with flagella carry water throughout sponge. Some cells act as filters for food and O2. Others digest the materials.

Structure Most sponges have spicules, spines made of hard material that provide shape and support for sponge.  Provide protection from other animals. Osculum: expels water that has been filtered.

Reproduction Asexual- budding. Sexual-  Male cells released into water, and sometimes female cells are also.  Fertilization occurs in the water or inside the cell wall.  Fertilized egg becomes larva: immature form of an organism.  Larva can swim and attach to ocean floor, where they become sessile.

Cnidarians Invertebrate Animals

Cnidarians: Phylum Cnidaria Found in water Jellyfish, corals, sea anemones, and hydras Eat plankton, fish, and clams Most are sessile, but can pull in food from around them.

Cnidarians All have tentacles– fingerlike extensions that go into the water. Specialized stinging cells for capturing prey and protection from predators.  Contains a nematocyst – has a filament inside that is released when prey comes in contact.  Wraps around or poisons prey  Cnidarians Cnidarians

Tissue and Body Systems Flexible layers of tissue that, along with cells, make up the body system. Organized around single body opening. Tentacles bring prey into the opening, which leads to a cavity (gut) where digestion takes place. Tissue and Body Systems

Even though they are sessile most their lives, they still move their bodies. Adult jellyfish swim. They sense and respond to prey that tough their tentacles; works like a simple nervous system, a network of nerve cells that form a nerve net.

Reproduction Buds are produced and carried away from the sessile parent in the water – asexual. Male cells are carried to female eggs, resulting in free swimming larva – sexual. Water is essential for cnidarian reproduction.

Life Cycle Jellyfish have several stages. When a larva settles on the ocean floor, it grows into a sessile polyp. The polyp develops buds that are eventually released; they are called medusas. A medusa is an adult jellyfish; mobile.

Body Plan Most have radial symmetry: the body is organized around a central point, the mouth that open to the gut. Allows them to capture food from all directions. Forces them to move by pushing down against the water to propel forward.

Worms Invertebrate Animals

Body Plan Most worms have bilateral symmetry: one half looks just like the other half. Have a forward end where the mouth is (its head) and a rear end for expelling wastes.

Worm body systems Some are simple, some are very complex. Tube-shaped body with a digestive tract. Take in oxygen through their skin, so must live in moist environments or water.

Segmented Worms – Annelida Bodies are broken into segments. Earthworms have organs that make up systems; digestive system leads to the excretory system to remove waste. Burrowing and feeding adds nutrients to the soil it goes through.

Segmented Worms – Annelida Several layers of muscle tissue. Hair-like bristles help anchor them to the soil. Nervous system with a brain and a nerve cord. Circulatory system with several hearts that pump blood throughout the body.

Segmented Worms – Annelida Can reproduce sexually or asexually. Earthworms have male and female parts on one worm. Worms exchange male rep. cells to fertilize their female eggs, which then hatch into larvae.

Flatworms - Simplest bodies Some move with cilia instead of muscles. Absorb nutrients through skin. Many are parasites, such as the tapeworm, that live off of their host organism.

Roundworms - They have muscles to moves; Nervous system and digestive system. Found almost everywhere on Earth; great decomposers on land and in water.

Dissection – directional terms Anterior: the front (head) end Posterior: the back (rear) end Ventral: the belly side Dorsal: the back side Lateral: the sides Medial: the middle

Dissection – anatomical terms Setae: small bristles that help anchor the earthworm Clitellum: larger glands between the segments; aids in reproduction Aortic arches: hearts Closed circulatory system: the blood remains inside of the blood vessels Open circulatory system: the blood flows out of the blood vessels

Dissection – anatomical terms Nerve ganglion: simple nervous system; like a brain Nerve cord: runs through entire worm; like spinal cord Dissection Video

Mollusks (mollusca) Invertebrate Animals

Mollusks All have soft bodies, and many have hard shells to protect them. Oysters, clams, snails, mussels, octopi, squids, and slugs, etc. Land, freshwater, and saltwater Most have well developed body systems.

Mollusks

Reproduce sexually All mollusks have a muscular foot and a mantle- a layer of folded skin that protects its internal organs.

Bivalves Shells that are made of two matching halves. When closed, the shell completed covers the body. No distinct head, but they have a mouth and sensory organs. Clams, oysters, mussels

Bivalves Filter-feeders: filter food from surrounding water. Moves by pushing its foot in and out of the shell; can burrow into the sand using foot.

Bivalves Takes in oxygen through gills- organs that filter dissolved oxygen from water. Made of many folds of tissue to create a larger surface area, allowing for higher oxygen intake. Gills also filter food from water.

Gastropods Most diverse group Land: snails and slugs Water: conches, whelks, periwinkles Most have spiral shaped shell.

Gastropods Head is at end of foot; has eyes and tentacles. Most have a radula: shreds their food Some eat animals, most eat plants/algae. Land = lungs; water = gills

Cephalopods Live in saltwater: octopi, squid, chambered nautiluses Most well-developed body system:  Brain  Nerves  Pair of eyes near mouth  Foot has tentacles for prey  Mantle moves water through the siphon for movement  Gills  Three hearts

Cephalopods

No protective shell, except nautilus – separate chambers mostly filled with gas to help float. Some change color, some release ink to confuse predators, move freely.

Adaptations This is a very diverse group that has adapted to survive in different types of environments. The foot  Bivalve: simple structure moving in and out of shell.  Gastropods: muscles in food allow organisms to glide over the surface to get food.  Cephalopods: foot has tentacles to pull food into mouth and help in movement.

Echinoderms (echinodermata) Invertebrate Animals

Echinoderms Live in the ocean. Adults have radial symmetry with mouth in the center. Feed off ocean floor. Sea stars, sea urchins, sea cucumbers, sand dollars

Spines and Skeletons They all have spines, some large (urchin) and some small (sea cucumbers). Skeleton is not made of bone – made of stiff, hard plates that lie just below the skin. Some are able to move with flexible skeleton (sea stars), some are not able to move (sand dollars).

Spines and Skeletons

Water Vascular System Water-filled tubes that radiate out from the center of the body. Tiny opening along top of body bring water into the tubes. Each tube has a series of tube feet at its base.

Tube Feet The tube feet have muscles that act like suctions to stick to the ocean floor. Tube feet can also help in finding and eating food: Sea star can surround clam, use tube feet to pull shell apart, and then use its stomach to start digesting the internal mollusk. Ocean Life

Arthropods (arthropoda) Invertebrate Animals

Arthropods Segmented body covered by a hard outer skeleton. Over ¾ of all invertebrates are arthropods. Insects, crustaceans (shrimp), arachnids (spiders). Appeared about 420 million years ago. Land and water dwelling

Exoskeleton and Jointed Parts Exoskeleton: strong outer covering made of chitin that completely covers the body. Has joints- where it is thin and flexible- to allow movement. Normally has three sections: head, thorax, abdomen.

Exoskeleton and Jointed Parts

Legs and other parts, such as antennae. Muscles attach in between segments to help arthropods move. They must shed their exoskeleton as they grow because it doesn’t; called molting

Body Systems Nervous system with brain and sensory organs Digestive system with stomach and intestines Open circulatory system – heart moves blood into the body directly with no blood vessels. Reproduce sexually.

Insects Three body segments, a pair of antennae, and six legs attached to the thorax. Obtain oxygen through spiracles. Many colors and shapes allow them to blend with surroundings. Compound eyes and antennae, wings, etc.

Insects

Many are herbivores with adaptations for the type of plant they eat. Butterflies have tube like mouths to reach nectar. Some insects help plants by acting as pollinators. Some insects harm plants by eating/crushing parts of their bodies.

Insects Some are social insects, like bees and ants, that live in groups to survive. They work together to find food, maintain shelter, and care for offspring. Usually one female, the queen, produces and lays eggs. (reproduce sexually) Bees

Insects Undergo metamorphosis during their life cycle, where their body structure changes dramatically. Complete: Begins as an egg, then larva, then pupa, and then adult. Incomplete/Simple: begin as egg, then hatches into a smaller version of the adult.  Also called direct development.  Complete vs. Incomplete Complete vs. Incomplete

Arthropods Invertebrate Animals

Crustaceans Most live in the water – lobster, crab, krill, copepods; some live on land – pill bugs. Three or more pairs of legs and two pair of antennae. Larger crustaceans have gills. Most have circulatory system – heart, no vessels Reproduce sexually; hatch from eggs.

Crustaceans – Eating Habits Some each plants and small animals (lobster/shrimp) Many are scavengers Some are filter feeders (barnacles) Beasts or Beauties?

Arachnids Exoskeleton, jointed limbs, segmented bodies; four pair of legs, no antennae, two body segments. Some are parasites (ticks/mites), others are predators (spiders/scorpions).  Predators sting, bite, or inject venom into their prey.

Arachnids Some get oxygen through spiracles. Some spiders have respiratory organs called book lungs.

Spiders Largest group of arachnids. Produce silk to spin webs to capture food. Silk comes out of spinnerets. Spiders

Millipedes Two pair of walking legs on each body segment. Move slowly and eat decaying leaves and plants. Emit foul odor that can harm predators.

Centipedes Move more quickly. One pair of walking legs per body segment. Antennae and jaw-like mouth, as well as pincers on their last segment. They are predators; use jaws/pincers to paralyze prey.