an invertebrate is an animal without a backbone. the group includes 95% of all animal species

Introduction to InvertebratesLaboratory 27 & 28

Introduction to Invertebrates

An invertebrate is an animal without a backbone.

The group includes 95% of all animal species

Introduction to Invertebrates

There is no escaping the invertebrates! Sharing space on your face

Introdcution to Invertebrates

Animals are distinguished by their body cavity or lack of.

Introduction to Invertebrates

Acoelomates› lack a body cavity (coelom)› bilateral symmetry › one internal space, the digestive cavity

Introduction to Invertebrates

Coelomates have a body cavity(s)

Digestive system and body wall can move independently

Internal organs can be more complex

Coelomic fluid can assist with respiration, circulation, excretion

Introduction to Invertebrates

The good the bad and the ugly!!!

Introduction to Invertebrates

Phylum Porifera Phylum Cnidaria Phylum Platyhelminthes Phylum Mollusca Phylum Annelida

Introduction to Invertebrates

Phylum Porifera Sponges

Sessile aquatic animals

Some are freshwater species, most are marine

shapes of their bodies are adapted to maximize the efficiency of the water flow

Introduction to Invertebrates

Phylum Cnidaria› (pronounced nidaria/ with a silent c)

› phylum containing over 9,000 species of animals found exclusively in aquatic and mostly marine environments

Jellyfish Hydra

Introduction to Invertebrates

Phylum Cnidaria Two basic body forms are seen : swimming medusa and sessile polyps

Introduction to Invertebrates

Phylum Cnidaria › Their distinguishing feature is a cnidocyte,

specialized cells that they use mainly for capturing prey.

Introduction to Invertebrates

Phylum Cnidaria Have no brains or central nervous systems

Instead they have nerve nets that generate signals in response to various types of stimulus, such as odors

Introduction to Invertebrates

Phylum Platyhelminthes Flatworms

› Planarian › Fluke› Tapeworm

no specialized circulatory or respiratory organs

Over half of all known flatworm species are parasitic, and some do enormous harm to humans and their livestock

oxygen and nutrients to pass through their bodies by diffusion

Introduction to Invertebrates

Phylum Platyhelminthes

Taenia solium

Introduction to Invertebrates

Phylum Mollusca› Considered coelomates

Coelom is limited to space around the heart

Introduction to Invertebrates

Phylum Mollusca

Introduction to Invertebrates

Phylum Mollusca

Introduction to Invertebrates

Phylum Mollusca

Introduction to Invertebrates

Phylum Mollusca› Respiratory system –gills› Digestive system – starts with Radula

Introduction to Invertebrates

Phylum Mollusca

Introduction to Invertebrates Phylum Mollusca

Introduction to Invertebrates

Cool Squid Stuff to look forDuring dissections

Introduction to Invertebrates

Phylum Annelida Segmented Most have a pair of coeloms in each segment which allows independent movement

Coelomatic fluid

*Moist environments

Introduction to Invertebrates› Phylum Annelida › Respiratory system

(usually) no specialized organs for gas exchange Thin, permeable body wall – surface for gas exchange

› Digestive system complete digestive system, with mouth and anus digestive tubes of earthworms have special structures, like a muscular wall

and a gizzard-peristalsis

Introduction to Invertebrates

› Phylum Annelida › Nervous system

two ventral nerve chords one relatively big nervous cell concentration

› Circulatory system› Closed› Move by peristalsis -waves of contractions and expansions› 2 main vessels

Dorsal moves blood anterior Ventral moves blood posterior

10X magnificati

on

Introduction to Invertebrates

› Phylum Annelida › Reproductive system – Varies

Asexual-budding

Sexual Earthworms

hermaphrodite

Introduction to Invertebrates

Phylum Annelida

support terrestrial food chains both as prey

aerating and enriching soil

Minnesota? Leeches ?

Introduction to Invertebrates Dissecting the earthworm

FOLLOW DIRECTIONS in your lab book

Allow 20 minutes