Kingdom Animalia

Remember…we’re talking about Kingdom Animalia

What characteristics do all members of the animal kingdom share?

Characteristics of Kingdom Animalia

1) Multicellular – what might be the benefit of being multicellular?

2) Eukaryotic – their cells each have membrane-bound organelles and a nucleus

3) Heterotrophic – animals are unable to obtain energy from the sun, so they need to consume other organisms

4) Animal cells lack cell walls (this, among other things, makes us different from plants!)

Animal Cell vs. Plant Cell

• Look at the diagram below. Notice animal cells are surrounded just by a cell membrane while plants have a cell membrane and a rigid cell wall

Cell Wall

Animal Kingdom has 2 Main Groups

Invertebrates• Lack a backbone• 97% of all species on Earth

are in this category

Vertebrates• Have a backbone for at least

part of their history• Only one phylum (Chordata)

Evolutionary Trends of K. Animalia

• If we examine the basic body plan of the members of K. Animalia, we find that they exhibit four major evolutionary trends:

1) Multicellular Development of Tissues

2) No symmetry Bilateral Symmetry3) 2 Germ Layers 3 Germ Layers4) Acoelomate (no gut) Coelomate (gut

surrounded by cells)

Trend #1 Multicellular Tissues

• Remember: multicellular means you are made up of more that 1 cell. Humans, for example, are made of trillions of cells

• The benefit of being a multicellular organism is that your cells can group together to form “tissues” that can them be specialized for different functions (i.e. become organs).

• Simple animals are multicellular; however they lack true tissues (e.g. sponges). In more complex animals, cells start to form tissues and simple organs

Types of Tissues Found in Complex Animals

Trend #2: Body Symmetry

• There are three main types of body symmetry: no symmetry(asymmetrical), radial symmetry, and bilateral symmetry

• Radial means you can divide the organism into more than 2 equal parts while bilateral means you can divide the organism into 2 like parts.

Trend #2: Body Symmetry

Why would it be beneficial to be bilateral?As you can see below, bilateral species have developed different body regions (anterior = head; dorsal = back) allowing these regions to specialize into different functions (head = sensory organs).

Trend #3: Development of Germ Layers

All animal life begins with a single fertilized egg

The single egg divides multiple times to form a small ball of cells called a blastula (yes you were once a blastula!)

The blastula later develops into “germ layers” (ectoderm, endoderm and mesoderm)

Trend #3: Development of Germ Layers

Each of these layers becomes specific tissues in an adult

Ectoderm – skin, nervous system (in more complex animals it also becomes feathers, scales, hair and nails)

Mesoderm – present in more complex animals. Forms organs of circulatory, reproductive, urinary and muscular system.

Endoderm – form lining of the gut

Why are germ layers important?

• Germ layers give us a hint as to how the complexity of organisms has progressed

• Lower invertebrates (sponges, jellyfish, etc.) lack a mesoderm (only have 2 germ layers) and therefore have no circulatory systems

• In more complex animals, a mesoderm layer (3rd germ layer) is present and it develops into important internal transport systems (digestive systems, circulatory systems, etc.)

Trend #4: Body Cavities

• Another evolutionary trend is the development of an internal body cavity called a coelom. A true coelom is lined by cells from the mesoderm germ layer.

• Some less complex animals groups have “pseudocoelom” (pseudo = false). This is a fluid-filled body cavity that is not surrounded by a layer of cells

• The simplest organisms lack coeloms and are therefore called “acoelomate.” In this case, the gut is not lined by cells or surrounded by a fluid-filled cavity.

Trend #4: Body Cavities

The red circle above is the gut. Notice in the pseudocoelomate, the gut is surrounded by a fluid-filled cavity. In the coelomate organism, the gut is surrounded by a layer of mesoderm cells (in blue).

Why is a coelom important?

• Having a coelom is beneficial because it helps to:– Protects internal organs– Streamlines the organism– Allows for the evolution of more complex organs

and organ systems

Common Animal Phylum

• Remember our organization of species???KingdomPhylumClass We are here!!OrderFamilyGenusSpecies

Animal Phylums

• There are around 30 to 40 different animal phylums (depending on the source you use), but we are only going to talk about 9 major groups:

1) Phylum Porifera “The Sponges”2) Phylum Cnidaria “Jellyfish/Coral”3) Phylum Platyhelminthes “The Flatworms”4) Phylum Nematoda “The Roundworms”5) Phylum Annelida “The Segmented Worms”6) Phylum Mollusca “Think Seafood - Clams, Oysters”7) Phylum Arthropoda “Insects”8) Phylum Echinodermata “Starfish”9) Phylum Chordata - What we consider “animals”

Phylum Porifera – “The Sponges”

Facts About Phylum Porifera

• Examples: Sponges• Irregular body shape (no symmetry)• Lack body tissues• Sessile (don’t move) and found at the bottom of oceans/lakes• Most primitive animals• These species are hermaphroditic (have both male and female

sex cells). Reproduce sexually by releasing these cells (only release one type at a time so they don’t fertilize eachother…think avoiding inbreeding!!)

• Also reproduce asexually by budding (broken off pieces can grow into new species)

• Lack nervous system, circulatory system, muscle tissue, etc .

Phylum Cnidaria – “Jellyfish, Coral”

Facts about Phylum Cnidaria

• Examples: Hydra, jellyfish, sea anemone, coral• Live in marine environment and some freshwater

(hydra)• 2 forms: free swimming and sessile• Have true tissues• Posses radial symmetry• 2 germ layers: endoderm and ectoderm• Reproduce sexually (male and female) and some

asexually (by budding)• Have nerve, muscle, and digestive tissues

Interesting Info on Cnidarians

• Did you know…Cnidarians capture food by shooting out specialized cells on their tentacles. These stinging cells can penetrate the skin of their prey or predators and inject toxic material. This material can then paralyze the target.

The sting of a jellyfish has claimed 2x the number of lives in Australia as compared to shark attacks!

Phylum Platyhelminthes – “Flatworms”

Facts about Phylum Platyhelminthes

• Examples: Tapeworm, planarian, fluke• Live in aquatic and terrestrial habitats; many are parasites• Show bilateral symmetry, have 3 germ layers (endoderm,

ectoderm and mesoderm) and lack a coelom (acoelomate)

• Reproduction: Hermaphrodites, reproduce sexually with one another, can regeneration from small pieces (asexual)

• Have true organs (simple ones for digestion and excretion)• Primitive brain with two nerve cords

Interesting Info on Platyhelminthes

• Many of these species are parasites of humans.

• One specific example is the tapeworm

• Inside your body, a tapeworm can grow up to 7 meters long!!

Phylum Nematoda – “Roundworms”

Facts about Phylum Nematoda

• Examples: Ascaris, Hookworm• Live in aquatic and terrestrial habitats; some are

parasites• Free-living, small, and relatively harmless• Bilateral symmetry, 3 germ layers,

pseudocoelomates (“false” coelom)• Reproduce sexually (separate sexes)• Digestive organs are present• Have a primitive brain and 2 nerve cords

Interesting Info on Phylum Nematoda

• A small number of this group are human parasites

• One example is Trichinosis. This is a disease causes by a roundworm parasite. The parasite can be found living in undercooked pork and transmitted to humans when we ingest it.

• Symptoms include abdominal pain, diarrhea, nausea and later muscle aches, itching, fever, chills, and joint pain.

• Roundworms are also common parasites of our pets (cats/dogs)

Phylum Annelida – “Segmented Worms”

Facts about Phylum Annelida

• Examples: Earthworm, leeches• Live in aquatic and terrestrial habitats; a few are parasites• Show bilateral symmetry, 3 germ layers, and have a true

coelom• This group of worms is “segmented” meaning it has

repeating units. This is an advantage because it permits greater specialization (head, thorax, abdomen)

• Reproduce sexually even though they are hermaphrodites• Have a simple circulation system and digestive organs• Nervous system includes an advanced brain, large nerve

cord, and smaller nerve-like cells called ganglia

Phylum Mollusca – “Seafood”

Facts about Phylum Mollusca

• Examples: Clam, oyster, octopus• Live in aquatic and terrestrial habitats• Have bilateral symmetry, 3 germ layers, and a true

coelom• Reproduce sexually. Some are hermaphroditic and

some have separate sexes (just male or female parts)• Have an open circulatory system• Filter-feeders• Primitive brain and light receptors

Phylum Arthropoda – “Insects”

Facts about Phylum Arthropoda

• Examples: Crayfish, spider, mosquito• Found everywhere• Bilateral symmetry, 3 germ layers, have a coelom

and undergo metamorphosis (change body form at different life stages i.e. caterpillar to butterfly)

• Reproduce sexually…are either male/female• Open circulatory system• One-way digestive tube (with mouth and anus)• Have definite brain with 2 nerve cords

Importance of Arthropoda• One of the most successful groups

of species• Insects are found everywhere…• There are over 750, 000 different

species• Insects are needed to pollinate

plants and grain crops• Also carry diseases (malaria and

sleeping sickness)• Compete with humans for food…

Billions of dollars every year are spent on insecticides to kill insects.

Phylum Echinodermata – “Starfish”

Facts about Phylum Echinodermata

• Examples: Starfish, sea urchin, sand dollar• Found in aquatic habitats• Radial symmetry/3 germ layers/have a coelom• Reproduce sexually….separate male and female. Also

able to regenerate (asexual reproduction). For example, a broken off piece of starfish can grow into a new starfish

• Open circulatory systems• 1 way digestive tube (separate mouth and anus)• Have nerve cords

Phylum Chordata – “Animals”

Facts about Phylum Chordata

• Members of this phylum are known as the “vertebrates.” A vertebrate is an organism that has a backbone.

• Only 5% of all known species belong in this group• Members of this group, at some point in their lives, all have a

backbone, nerve cord, and gills• Examples: Whale, Humans, Dogs, Fish, Frog• What type of symmetry do they possess?• 3 germ layers and a true coelom• Reproduce sexually….separate males and females• Complex heart and closed circulatory system• Large brain, protected by a skull, and advanced nervous system

Class Mammalia

• There are many classes that belong to the phylum Chordata, but the most common to us is the Class Mamalia.

• All members of this group are warm-blooded, air breathing, 4-legged vertebrates that are covered with hair and sweat glands.