Animal Diversity I

BIOB 171

Introduction• Domain Eukarya, Kingdom Animalia• Heterotrophic – obtain food by ingesting

other organisms or their by-products• Arose some 565 mya – Cambrian Explosion

Cambrian Explosion

• 565 to 525 million years ago• Lasted for ~40 million years – very fast!• 4 billion years, nothing but bacteria, plankton,

and algae existed.• Most single celled or colonies.• Then Cambrian Explosion…• All major animal body plans appear in the

fossil record during this period.

Parazoa

Turn to page 181 in your lab manual and look at figure 1.35 major groups – we’re looking at 9Each group has a different body planParazoa - asymmetrical

Eumetazoa• All are multicellular animals

• Organisms in this group have either radial or bilateral symmetry

• It is a sub-kingdom that includes everything except sponges and a few other random animals.

A little more detail…

• Domain Eukarya, Kingdom Animalia, Sub-kingdom

Eumetozoa

• Heterotrophic – obtain food by ingesting other organisms or

their by-products

• Lack cell walls

• Pass through a blastula stage

• Arose approx. 620 - 550 mya

Protostomes vs. Deuterostomes

• Protostomes – blastopore becomes mouth• Deuterostomes – blastopore becomes anus

Protostomes

Deuterostomes

Parazoa

Radialaria

Protostomes

• Two large groups:– Lophotrochozoa – The name is based on the

trochophore larva found in within this group. Includes annelids, molluscs, flatworms, and rotifers

– Ecdysozoa – Animals in this group undergo molting (ecdysis) or the shedding of an outer body cover. Includes roundworms, nematodes, arthropods (and others).

Porifera

Cnidaria

PlatyhelminthesRotifera

MolluscaAnnelida

Basic Characteristics of Animals

Pages 181 – 183• Read through and understand all 13 characteristics• Understand Figure 1, understanding the

differences between (a) and (b).• As you move through the lab looking at organisms

and doing the dissections, refer to these characteristics.

• Record your observations in your lab notebook and fill out the table that I handed out. You will be able to use this table on the final exam.

Phylum Porifera – Sponges Exercise 1

• Unique body form that contains NO tissues and NO symmetry.• Observe preserved specimens and slides• Osculum – large opening to the body at one end, opposite end

attaches sponge to substrate• Spicules – needle-like projections around the osculum and protruding

from the surface of the body – made of calcium carbonate – give support and protection and prevent small animals from entering the sponge’s internal cavity.

• Choanocyte or collar cell – unique to sponges, line the central cavity and channels – each has a flagellum extending from its surface into the water – their collective beating moves water through the sponge body wall – small food particles are taken up and digested by collar cells – cause water to move in through the channels and out the osculum.

Phylum Cnidaria – Hydras (Hydra) Exercise 2• Two tissue types, no complex organs• Includes: corals, jellies, sea anemones, and

Portuguese men-of-war.• Most species are marine, few freshwater spp.• Two body forms present in the life cycle:– Umbrella-like, free-swimming stage– Cylindrical, attached or stationary form – often grows

into colonies of individuals• Observe live hydra in a depression slide.• Also observe prepared slides

Phylum Platyhelminthes Planarians (Dugesia)

Exercise 3

• Free-living flatworms• Bilaterally symmetrical, dorso-ventrally flattened• 2 tissue types• Found under rocks, leaves, and debris in freshwater

ponds and creeks• Move using muscles in their body and cilia on their

ventral side• Feed by extending a long tubular pharynx of their

mouth, located on the ventral side of the body.• Observe live Dugesia (feed liver) and prepared slides

Pharynx also functions as the anus

Phylum Rotifera - Rotifers

• NOT IN LAB MANUAL• Very small animals – most 0.1 – 0.5

mm in length• Most common in freshwater, though

some salt water species• Important part of freshwater

zooplankton, being a major food source and many species contributing to decomposition of organic matter.

• Pharynx contains tiny, calcified, jawlike structure called trophi

Phylum Annelida - Exercise 4Clamworms (Nereis) and Earthworms (Lumbricus terrestris)

• Diverse group of animals that inhabit a variety of environments.

• Sizes range from microscopic to several meters in length

• Segmented “worms”• Most species are marine, living free in the

open ocean or burrowing in ocean bottoms.• Others live in freshwater or in soils• Leeches are parasitic

Clamworms (Nereis) Exercise 4: Lab Study A

• Dissect in pairs. Use lab manual and see handouts on tables.

• Commonly found in mud flats and on the ocean floor.

• Burrow in sediments during the day and emerge to feed at night.

• Each segment bears fleshy outgrowths called parapodia.

• At the end of each parapodium there are several terminal bristles called setae

Earthworms (Lumbricus terrestris)Exercise 4: Lab Study B

• Dissect in pairs. Use lab manual and handouts on tables.

• You will also look at prepared slides

Phylum Mollusca Exercise 5

• Thousands of species with great diversity in form

• Most species are marine, but others live in freshwater or on land.

• Economically important as a food source for humans.

Mollusk Characteristics:

1. A hard external shell for protection.2. A thin structure called the mantle, which

secretes the shell3. A visceral mass in which most organs are

located4. A muscular foot used for locomotion.

Each pair will dissect a clam.

Last Notes

• Remember to record your observations in your lab notebook and fill out the table I handed out.

• Observed ALL specimens on display, they will all be fair game on the practical unless I say otherwise.

• Next week Animal Diversity II – read pgs. 201-211