Section 7: Overview of Animal Diversity (Part B)

95%

Invertebrates are what percent of known animal species?

1. a flat bilayer of cells

2. silk-spinning glands

3. tentacles covered with suction cups

Diversity of forms and features of invertebrates that result from vaied environments? [3]

Microscopic to 18m long

Invertebrates length range

All animals except sponges and a few other groups

what animals belong to the clade Eumetazoa

Eumetazoa

Clade of animals with true tissues

Phylum Cnidaria

Phylum that has a wide range of both sessile and motile forms

Cnidaria

Phylum radial body plan, diploblastic.

Gastrovacular cavity

A sac within Cnidaria with a central digestive compartment

Hydra

Model animal in Cnidaria

Mouth and anu s

Opening to the gastrovacular cavity functions as what?

Mesoglea

a gelatinous layer between the epidermis and gastrodermis in Cnidaria

1. outer layer of epidermis

2. inner layer of gastrodermis

2 layers of body wall of cnidaria:

Ectoderm

epidermis arises from what?

Endoderm

Gastrodermis arises from what?

1. sesile polyp

2. motile medusa

Two variations of Cnidaria body plan:

Polyps

Cylindrical Cndaria, adheres to sustrate by the aboral end of the body (opposite mouth)

Tentacles

Polyps extend this, waiting for prey

1. Hydras

2. sea anemones

Polyps examples include: [2]

Hydra

Freshwater Cnidarian that exists only in polyp form

Asexual budding

How do hydra reproduce

Medusa

flattened, mouth-down version of polyp

Moves freely in water by passive drifting and constractions of bell-saped body

How do medusa move?

Free-swimming jellies

Medusa include what?

Dangle from oral, downward-pointing surface

Describe medusa tentacles

Use tentacles around mouth to capture prey and push foo dinto gastrovascular cavity

function of Cnidarian tentacles

Gastrovascular cavity

where does cnidarian digestion begin?

Cnidocytes

Cnidarian tentacles are lined with these unique cells

Function in defence and prey capture

Cnidocyte cell function

Nematocysts

Some cnidocytes contain these organelles that contain and eject a stinging thread that can penetrate the body wall of prey

When a “trigger” is stimulated by touch or certain chemicals, the thread shoots out puncturing and injecting toxins into prey

How do nematocysts work

1. tentacles push food into gastrovascular system

2. enzymes secreted into cavity

3. cells lining cavity absorb nutrients and complete digestino

4. undigested remains are expelled through mouth/anus

Describe digestive system of cnidarians:

Hydrostatic skeleton

Gastruvascular cavity acts as this against which contractile cels work

Coordinated by nerve net. can detect and respond to stimuli from all directions (no brain)

how are cnidarian movements coordinated??

Volume of the cavity is fixed, contraction of cells causes animal to change shape.

what happens when cnidarian closes mouth

Bilateria

Majority of animals belong to the clade:

1. has bilateral symmetry and triploblastic

2. most have coelom and a digestive tract with two openings

Describe clade Bilateria

2

how many openings does bilateria digestive tract have?

1. Lophotrochozoa

2. Ecdysozoa

3. Deuterostomia

The clade bilateria contains:

By molecular data

how was the clade Lophotrochozoa identified

lophophore

A crown of ciliated tentacles for feeding in lophotrochozoa

trochophore larval stage

Stage that some Lophotrochozoa pass through

18

Lophotrochozoa includes how many phyla?

1. flatworms

2. rotifers

3. ectoprocts

4. brachiopods

5. molluscs

6. annelids

Lophotrochozoa includes which organisms? [6]

Annelids (“little rings”)

Segmented worms

Segmentation

Division of body into nearly identical subunits. Body composed of series of fused rings, that are distinct segments separated by partition

Septum

Partition that separates body subunits in segmented animals

1. sea

2. most freshwater habitsts

3. damp soil

where do annelids live [3]

1. errantia

2. sedentaria

Two major claves of annelids (based on lifestyle differences)

leeches

earthworms

Sedentaria annelids include: [2]

most live in frenshwater

some are marine or terrestrial

Where do leeches live

1. anaesthetic

2. chemical that keeps blood from coagulating

Leeches secrete what?

Hirudin

chemical secreted by leeches that keeps blood from coagulating

1. predators of invertebrates

2. parasites that such blood by temporarily attaching to other animals

leeches include: [2]

1. through soil

2. extract nutrients as the soil moves through alimentary canal

How do earthworms eat?

They are hermaphrodites but cross fertilize

some reproduce asexually by fragmentation

How do earthworms reproduce

Ecdysozoans

Organisms that are covered by a touch coat called a cuticle

Cuticle is shed or moulted through a process called ecdysis

What happens when cuticle is shed in Ecdysozoans

1. nematodes

2. arthropods

Two largest phyla of ecdysozoans

1. segmented body

2. hard exoskeleton

3. jointed appendages and paired

Arthropod body plan:

1. walking

2. feeding

3. sensory reception

4. reproduction

5. defense

Arthropod appendages can be modified for: [5]

the cuticle

Entire body of arthopod is completely covered by:

layers of protein and the polysaccharide chitin

Arthropod exoskeleton is made of:

1. protects

2. provide attachment points for muscles that move appendages

3. prevents desiccation

function of arthropod exoskeleton [3]

it moults. becomes vulnerable until new exoskeleton has hardened

what happens to arthropod exoskeleton when it grows

1. eyes

2. olfactory receptors

3. antennae

Well developed sensory organs in arthropods: [3]

1. touch

2. smell

Function of arhtropod antennae [2]

Concentrated in anterior end

Where are sensory organs concentrated in arthropods?

Open circulatory system

Circulatory system in arthropods

Hemolymph

Fluid propelled by arthropod heart by short arteries into sinuses surrounding tissues and organs

the hemocoel

Hemolymph-filled body sinuses in arthropods

Hemocoel (coelom is reduced)

Main body cavity in adult arhtropods

1. insects have trachael systems

2. branched air ducts leading to interior from pores in cuticle

organs specialized for gas exchange have evolved in arthropods:

• Hemolymph fluid propelled by heart
through short arteries into spaces (sinuses)
surrounding tissues and organs
• Hemolymph reenters heart through pores
that have valves

Describe arthropod open circulatory system:

1. cherlicerates

2. myriapods

3. Pancrustaceans

Three major lineages that diverged early in arthropod evolution: [3]

1. sea spiders

2. horseshoe crabs

3. scorpions

4. ticks

5. mites

6. spiders

examples of cherlicerates: [6]

1. centipedes

2. millipedes

Examples of myriapods: [2]

1. lobsters

2. shrimp

3. other crustaceans

4. insects and their relatives

examples of pancrustaceans: [4]

1. grasshoppers

2. crickets

3. katydids

Orthoptera insects include: [3]

1.head

thorax

abdomen

three body regions of insects:

3

how many pairs of legs to insects have

obvious segmentation of thorax and abdomen

segments that form the head are fused

insect segmentation:

1. escape predators

2. find food and mates

3. disperse t new habitat

4. faster

advantages of flight in insects:

Many have one or two pairs of wings that emerge from the dorsal side of the thorax

how many wings do insects have:

Incomplete metamorphosis

metamorphosis where the young are called nymphs

Complete metamorphosis

Metamorphosis that has larval stages known by such names as maggot, grub, caterpillar

nymphs

Young insects that resemble adults but are smaller and lack wings

1. alrva (caterpillar) eats and grows and moults

2. larva develops into pupa

3. within pupa larval tissues broken down, adult buil by division and differentiation of cells quiscent into larva

4. eventually adult emerges

caterpillar metamorphosis stages [4]