Do First Grab the introductions to animals worksheet and the invertebrate packet

Introduction to Animals Chapter 26

What characteristics do all animals share? They are multicellular Their cells are eukaryotic and lack walls They are heterotrophic by ingestion They mainly reproduce sexually They are able to move

How are Animals Classified? BY THE LACK OR PRESENCE OF TRUE TISSUES True tissues are groups of similar cells that perform a common function Ex: Muscle Tissue

How are Animals Classified? BY BODY SYMMETRY Asymmetry is the lack of body symmetry Radial symmetry is when body parts are arranged in a circle around a central axis Bilateral symmetry is when the body can be divided equally along one plane

How are Animals Classified? BY THE PRESENSE AND TYPE OF INTERNAL BODY CAVITY 1.) Acoelomate No body cavity 2.) Pseudocoelomate No true body cavity 3.) Coelomate True body cavity Fluid-filled space b/t body wall and gut

How are Animals Classified? WHETHER OR NOT THE BODY IS ASSEMBLED IN SEGMENTS

How are Animals Classified? BY THE PRESENSE OR ABSENCE OF JOINTED APPENDAGES Joints permit powerful movement and aid in locomotion. Allow animals to perform complex movements

How are Animals Classified? WHETHER THEY DEVELOP IN A DEUTEROSTOME OR PROTOSTOME PATTERN In protostomes, the mouth is formed first, then the anus In deuterostomes, the anus is formed first, then the mouth

Notes 1. Take out your note packet 2. Think to yourself: What is one way that animals are classified?

Phylum Porifera

Members Sponges – the simplest animals

Body Structure Asymmetrical No tissues or organs Openings called pores (or ostia) cover body wall Cells are suspended in jelly like layer called mesoglea “Skeleton” made of spicules

Feeding Sponges are filter feeders – they filter plankton from sea water Water enters through ostia and waste exits through oscula Ostia

Movement Adult sponges are sessile – they are attached to the ocean floor and cannot move Larvae can swim

Reproduction Asexual: Budding and/or fragmentation Sexual: Sperm is released and fertilizes egg that is retained in sponge Free swimming larva swims to another location where it remains and develops into a new adult

Unique Characteristics Spicules Asymmetry Collar Cells

Phylum Cnidaria

Members Hydras; Corals; Jellyfish; Sea anemones

Body Structure Radial Symmetry Body composed of outside (ectoderm) & inside (endoderm) layers No body cavity Jelly fish have hydrostatic skeleton (water filled cavity) that is under pressure

Feeding They are predators – they capture prey w/ stinging tentacles using cnidocytes Gastrovascular cavity allows for 2 way feeding

Movement Cnidarians have two body forms Medusa: Free floating; mushroom shaped Polyp: Attached to rock; pipe shaped

Reproduction Asexual: by budding Sexual: Release gametes into water After fertilization, the larva is free-swimming The larva then develops into an adult

Unique Characteristics Cnidocytes (stinging cells) Nematocyst Cnidocyte

Phylum Platyhelminthes

Members Flatworms: Tapeworms, flukes, planarians

Body Structure Bilateral Symmetry Anterior/posterior Dorsal/ventral Sense organs grouped at the anterior end Better to sense where you are going than where you have been (foreshadows brain) Three tissue layers (ecto, meso, endoderm) – no coelom Ocelli function as eyes

Feeding One opening allows for 2 way digestion The opening is called the pharynx and is found on the ventral side in the middle

Movement Muscles found in mesoderm aid in movement Bilateral symmetry, nerves at one end (ganglion), and ocelli allow for movement in forward direction

Reproduction Asexual: Regeneration Sexual: Many are hermaphroditic This characteristic is common in parasites… why?

Unique Characteristics None

Phylum Nematoda

Members Roundworms Ex: Hookworms; pinworms; heartworms Elephantiatis is caused by a type of roundworm blocking the lymphatic system, causing limbs to swell

Body Structure Bilateral Symmetry Not Segmented Three tissue layers Pseudocoelom Nerve cells and sensory cells located towards head

Feeding The digestive system has separate openings for feeding and waste elimination (one-way!) Not very differentiated This allows them to acquire more food, which increases their activity level

Movement Long layers of muscle that pull against the body’s outer covering and the pseudocoelom whips the worm’s body from side to side Better coordinated than acoelomates

Reproduction Usually reproduce sexually

Unique Characteristics None

Phylum Mollusca

Members Snails, slugs, octopus, squid, oysters, mussels, and others

Body Structure Bilateral Symmetry Three tissue layers with TRUE COELOM (reduced in size) Isolates the internal organs from body-wall movements, allowing for increased activity level and increased organ complexity Have soft bodies (some have shells) Not segmented Organ systems for excretion, circulation, respiration, digestion, reproduction

Feeding Most have a radula which scrapes food off of rocks or plant matter Food is digested in the stomach and intestine of the one way digestive tract Wastes are passed out of the anus

Movement Widely varied Some glide along surface (ex: snails) Some shoot water out of a siphon to propel themselves; or, creep along using suction cups (octopus) Some are mostly sessile, but can open and close their shells quickly to propel themselves (mussels)

Reproduction Sexes are usually separate Fertilization occurs externally in most aquatic mollusks Fertilization occurs internally in most terrestrial mollusks and octopuses Larva is called trocophore

Unique Characteristics Radula – used to scrape food off of surfaces

Phylum Annelida

Members Segmented worms: Earthworms, marine worms, & leeches

Body Structure Bilaterally Symmetrical Have segmentation: Repeated sections of body that contain complex sets of body structures Three tissue layers Coelom Organ systems for excretion, digestion, circulation, sensing, etc…

Feeding Separate openings for mouth and anus Eat organic waste material They excrete digested material (called castings) that helps maintain nutrient-rich soil Leeches are sanguivorous - they feed as blood sucking parasites on preferred hosts.

Movement Annelids use their hydrostatic skeleton to move from one place to another Their characteristic crawling motion is due to different sets of muscles lengthening and shortening at different times Peristalsis Video

Reproduction Asexual by fragmentation Sexual Some are hermaphroditic Some have separate sexes

Unique Characteristics None

Phylum Arthropoda Jointed Feet

Members Crustaceans, Spiders, & Insects

Body Structure Bilaterally Symmetrical Three tissue layers Coelom Segmented Covered with an exoskeleton made of chitin Jointed & waterproof Well developed brain and sense organs

Feeding Arthropods have a completely differentiated digestive system (each part as a special job) They can be carnivores, herbivores, detritus feeders, filter feeders, and parasites Typically, paired appendages around the mouth are used for collecting and handling food and are usually specialized according to their diet

Movement Joints permit powerful movement and aid in locomotion Muscles in arthropods are attached to the endoskeleton across joints Different groups of arthropods are adapted for movement on land, water, & in the sky

Reproduction Sexes are usually separate Fertilization usually occurs externally In many species, such as spiders, the young look like miniature adults The young of other arthropod species have little or no physical resemblance to adults and go through metamorphosis

Unique Characteristics Jointed exoskeleton made of chitin

Phylum Echinodermata Spiny Skinned

Members Sea urchins, brittle stars and sea cucumbers

Body Structure Have an endoskeleton made of calcium Bilateral symmetry as larvae; radial symmetry as adults Nervous system called “nerve ring” allows them to perform complex movements Have a coelom (body cavity) that functions as a simple circulatory and respiratory systems

Feeding One-way digestion (mouth on ventral side; anus on dorsal side) Echinoderms can eat by ejecting their stomachs out of their mouths onto a food source and “slurping up” the food source once it has been digested by stomach enzymes Sometimes, their food sources are harder to get to – they can use their tube feet to suction open a prey item before digesting it

Movement Echinoderms have hundreds of tube feet on their ventral side that act as little “suckers” The tube feet allow them to crawl along surfaces http://www.youtube.com/watch?v=KIIy0vj6wQE&feature=related

Reproduction Some are hermaphroditic; some have separate sexes Asexually: Fragmentation (if an arm breaks off, it can develop into a whole new organism) Sexually: Females and males release their gametes (eggs and sperm) into water, where fertilization occurs

Unique Characteristics Nerve Ring Tube feet