Lecture Exam #2

Animal Kingdom Intro Summary

Animal Kingdom Intro Summary

1. animals are efficient consumers of other organisms

2. Most have adaptations that help them detect, capture, eat, & digest other organisms

3. There are exceptions to nearly every criterion for distinguishing animals from other life-forms

Animal Kingdom Characteristics (5 characteristics)

1. Animals are heterotrophs that ingest their food

2. Animals are multi-cellular eukaryotes

3. Cells are supported by structural proteins such as collagen, rather than cell walls

4. Most animals reproduce sexually, with the diploid stage usually dominating the life cycle

5. Most animals have at least 1 larval stage

Larva Definition

A sexually immature & morphologically distinct from the adult; it eventually undergoes metamorphosis to become a juvenile

Juvenile Definition

An individual animal that resembles an adult, but is not yet sexually mature

The common ancestor of all living animals

Group of protists called choanoflagellates

Invertebrate Characteristics

-Animals that lack a backbone -account for more than 95% of known animal species -are morphologically diverse & occupy almost every habitat on Earth

Phylum Porifera General & IMPORTANT Characteristics

-Level of organization: cellular (no tissues, just cells) -Asymmetric **-**No germ layers **-**No body cavities **-**Most sponges are MARINE

Phylum Porifera Trivial Characteristics

1. Sessile sponges are filter feeders

2. Porifera means "pore-bearing"

   1. bodies perforated by many pores

3. Skeleton is composed of spicules

4. Sponges can regenerate

5. Few sponges live in brackish water & fresh water

6. Many species are brightly colored because of pigments in dermal cells

7. Some stand erect, some are branched, & some are encrusting

Cell types of Sponges

Choanocytes & ameobocytes

Choanocyte Definition

Flagellated collar cells & generate a water current through the sponge, & ingest suspended food

Amoeobocytes

Totipotent cells found in the mesohyl that play roles in digestion & manufacture skeletal fibers

• digest food → transfer food to other cells → make skeletal fibers (they help the sponge stand upright)

The mesohyl of the sponge

A gelatinous noncellular layer between 2 cell layers

• holds the two layers together

Hermaphrodite Sponges

Each individual functions as both male & female (they produce both sperm & egg)

3 classes of the Phylum Porifera

1. Calcarea

2. Hexactinellida

3. Demospongiae classes are separated by their skeletons (which are made by amoebocytes)

Calcrea Class of Sponges (Calcispongiae) Characteristics MEMORIZE

1. Typically have calcium carbonate (calcareous) spicules with 1, 3, or 4 rays -spicules are straight or have 3 or 4 rays

2. Most are small with tubular or vase shapes

3. Many are drab in color, but some are bright yellow, green, red, or lavender

4. Asconoid*,* syconoid*, &* leuconoid body forms

Hexactinellida Class of Sponges MEMORIZE

1. Glass sponges with 6-rayed siliceous spicules

2. Nearly all are deep-sea forms

3. Most are radially symmetrical

4. Stalks of root spicules attach them to substrate

Demospongiae Class of Sponges MEMORIZE

1. Have siliceous spicules, spongin fibers, or both

2. contains 80% of living sponge species

3. spicules are siliceous but NOT 6 rated

4. absent or bound together by spongin

5. Leuconoid body form

6. All marine except for Spongillidae (genus), the freshwater sponges

7. freshwater sponges are widely distributed in well-oxygenated ponds & springs, they flourish in summer & die in late autumn

Homoscleromorpha

Previously a subgroup of Demosphongiae but pinacoderm has a basement membrane

Pinacoderm of Sponges

the outer layer of a sponge body made up of pinacocytes (equivalent of the epidermal layer of other animals)

Types of Canal Systems for Phylum Porifera (NEED TO MEMORIZE)

1. Asconoids

2. Syconoids

3. Leuconoids

Asconoid canal system of Sponges (memorize)

-Flagellated spongocoels -simplest body form -Small & tube shaped (has a center cavity) -Water enters a large cavity, the spongecoel -Cavity is lined with CHOANOCYTES -All calcarea are aconoids -leucosolenia & Clathrina are examples

Spongecoel

Large central cavity of sponges

• water enters the spongecoel through hundreds of tiny pores, ostia, & exits through the large opening, the osculum

osculum (singular) & oscula (plural)

an excretory structure in the living sponge, a large opening to the outside through which the current of water exits after passing through the spongocoel

Syconoid canal system of Sponges (memorize)

1. Resembles asconoids but larger with a thicker body wall

2. Wall contains choanocyte-lined radial canals that fold back & forth to make canals, & then empty into the spongeocoel

3. Water enters the radial canals through tiny openings, called prosopyles, & then to radial canals, then apopyle to spongeocoel

Apopyles of Syconoid Canals in Sponges

One of the openings by which the water passes out of the radial canal or the flagellated chamber of a sponge

Prosopyles Syconoid Canals in Sponges

a pore through which water is drawn from the outside into one of the saclike chambers formed by the evagination of the body wall

Spongocoel of Syconoids

Spongeocoel is lined with epithelial cells rather than choanocytes

Leuconoid Canal System of Sponges

1. Flagellated Chambers

2. Most complex & larger with many oscula

3. Clusters of flagellated chambers are filled from incurrent canals, & discharge to excurrent canals

4. most sponges are leuconoid

Leuconoid system, MEMORIZE

evolved independently many times in sponges

• system increased flagellated surfaces compared to volume

  • more collar cells can meet food demands

Sexual Reproduction of Sponges

1. Most are monoecious: male & have female sex cells in 1 individual

2. sperm sometimes arise from transformed choanocytes

3. the free-swimming larva of sponges is a solid parenchymula, or a zygote

Asexual Reproduction of Sponges

1. Can occur by bud formation or fragmentation

   1. External buds: budding

   2. Internal buds or gemmules

2. formed by archaeocytes that collect in the mesohyl -coated with tough spongin & spicules -survive harsh environmental conditions

Animal Architecture Components

1. Body Symmetry

2. Reproduction & Development

3. Body Cavities

4. Germ Layers 4a. Type

Animal Body Planes: Symmetry Definition

Balanced proportions of parts on opposite sides of a median plane

Types of Symmetry for Animal Body Planes

1. Asymmetry

2. Radial Symmetry

3. Bilateral Symmetry

Asymmetrical Body Plane Definition

No plane through which they can be divided into identical halves

• sponges (not a lot of animals are asymmetrical)

Radial Symmetry

1. Body divided into similar halves by more than 2 planes passing through the longitudinal axis

2. Usually found in sessile, free floating, or weakly swimming animals

3. no anterior or posterior end

   1. Can interact with the environment in all directions

   2. 2 phyla (plural of phylum) are Cnidaria & Ctenophora

Bilateral Symmetry

1. Organisms can be divided along a sagittal plane into two mirror portions

   1. Right & left halves

2. Much better fitted for directional (forward) movement

3. Associated with cephalization: differentiation of a head region with a concentration of nervous tissue & sense organs

4. Advantageous to an animal moving through its environment head first

Reproduction & Development

1. Most animals reproduce sexually, with the diploid stage usually dominating the life cycle

2. Sequence of inherited developmental begins after the fertilization of an egg to form a zygote

3. The zygote undergoes rapid cell division called cleavage

4. Cleavage leads to the formation of a multicellular, hollow blastula

5. Sponges & cnidarians lack a distinct cleavage pattern

6. Bilateral animals typically exhibit either radial or spiral cleavage

Cleavage Definition, with regard to reproduction & development

The rapid cell division, mitosis, of a zygote

Morula

1. a solid ball of cells resulting from division of a fertilized ovum, and from which a blastula is formed

2. A ball of cells made through cleavage

Blastula Definition

Multicellular hollow ball of cells

• The embryo is a blastula

Invagination where gastrulation begins

infolding of cell sheet into embryo

invagination is the first step of gastrulation, which is the process by which the three germ layers of the embryo are formed. During gastrulation, the invagination of the blastula forms the archenteron, which will eventually become the gut of the organism.

Blastocoel

the fluid-filled cavity of a blastula

Gastrula

The blastula becomes this 2 layered stage, with an endoderm & ectoderm layer

Gastrocoel

The inner body cavity that is surrounded by the endoderm

Gastrulation

In animal development, a series of cell and tissue movements in which the blastula-stage embryo folds inward, producing a three-layered embryo, the gastrula.

Types of cleavage (cell division) that Bilateral animals exibit

Radial or spiral

Radial cleavage

The cleavage are symmetrical to the polar axis & produce layers of cells on top of each other in the early embryo

Spiral clevage

Cleaves oblique & typically produce a quartet that come to lie not on top of each other but in furrows between the cells

Definition & Functions of Body Cavities

• a hollow space within the body that is lined by a membrane and contains bodily organs

1. Most animals possess a body cavity

2. A true body cavity is called a coelom & is derived from the mesoderm

3. Fluid in the cavities cushion the suspended organs

4. Fluid in the cavities acts like a skeleton against which muscles can work

5. The cavity enables internal organs to grow & move independently of the outer body wall

Coelom Definition

A true body cavity & is derived from the mesoderm

Coelomates

An animal that possesses a true coelom; a body cavity lined by tissue completely derived from mesoderm

pseudocoelom

A body cavity derived from the mesoderm & the endoderm

Pseudocoelomates

triploblastic animals that possess a pseudocoelom -round worms

Acoelomates

Triploblastic animals that lack a body cavity

types of coelomates

1. Schizocoely

2. Enterocoely

Schizocoely Formation

Mesodermal cells migrate to the blastocoel

Entercoely Formation

Coelom comes from pouches off the archenteron, or primitive gut, that pushes outward into the blastocoel

Germ Layers

During development, 3 germ layers give rise to the tissues & organs of the animal embryo

Ectoderm Germ Layer

The germ layer covering the embryo's surface Develops into epithelial tissue & the nervous system

Endoderm Germ Layer

The innermost germ layer & lines the developing digestive tube, called the archenteron

Archenteron

The developing digestive tube

Mesoderm Germ Layer

the middle layer of cells -layer of cells & tissues between your skin & digestive system: muscles & bones

Diploblastic animals have which germ layers?

Ectoderm & Endoderm -includes cnidarians & a few other groups

Triploblastic Animals have which germ Layers

ectoderm, endoderm, & mesoderm -mesoderm is an intermediate tissue layer

Types of Triploblastic Organisms

1. Deuterostomes

2. Protostomes

MEMORIZE Deuterstome Development & Definition

1. the blastopore becomes the anus

2. The name means "second mouth," which refers to the formation of the mouth from the second opening in the embryo

3. 3 phyla: Echinodermata, Hemichordata, & Chordata

MEMORIZE Protostome Development & Definition

1. The name means "first mouth" & refers to the formation of the mouth from the embryonic blastopore

2. The anus forms secondarily protostomes

MEMORIZE Characteristics of Phylum Cnidaria

1. Contain specialized cells: cnidocytes 1a. typically housing stinging organelles called NEMATOCYSTS

2. All are aquatic & mostly marine

3. Have Radial symmetry

4. Diploblastic

   1. Epidermis: outer skin layer → ectoderm

   2. Gastrodermis: outer skin layer of the digestive tract → endoderm

   3. Contains a mesoglea

5. No coelomic cavity

6. Two body types

   1. free-swimming medusae: looks like a jellyfish

   2. sessile polyps: non-moving

7. Incomplete gut or gastrovascular spaces

8. Hydrostatic skeleton

9. Nerve Net

10. Asexual & sexual reproduction

Cnidocytes

Special stinging structures on cnidarians that look like small harpoons

Nematocysts

specialized organelles within cnidocytes that eject a stinging thread

Mesoglae

Extracellular matrix (non-living) that lies between the ectodermis & gastodermis

2 Body Types of Cnidarians

1. Free-swimming medusae

2. Sessile polyps

Cnidarians having an incomplete means...

they only have 1 opening

Hydrostatic skeleton

A fluid skeleton in many soft-bodied invertebrates, including annelids, that allows an organism to change shape but not volume

• a cavity filled with water; the water is incompressible, so the organism can use it to apply force or change shape

4 Classes of Cnidaria

1. Hydrozoa

2. Scyphozoa

3. Cubozoa

4. Anthozoa

Hydrozoa Class of cnidarians

Hydroids, Portuguese man of war

Scyphozoa Class of Cnidarians

Jellyfish

Cubozoa Class of Cnidarians

Cube (box) jellyfish

Anthozoa

sea anemone & corals

Cnidarians Capturing Prey

1. Cnidarians are carnivores that use tentacles to capture prey

2. The tentacles are armed with cnidocytes, unique cells that function in defense & capture prey

3. Nematocysts are specialized organelles within cnidocytes that eject a stinging head

4. Each nematocyst is covered by a little lid: an operculum

5. Except in Anthozoa, cnidocytes are equipped with a larger structure: cnidocil

6. After discharge, a cnidocyte is absorbed & another develops

Cnidaria Body Plan and Symmetry

1. They have 2 basic body plans: Polyp & Medusa

Polyp Body Plan of Cnidarians

1. Hydroid form

2. Adaptation to a sedentary life

3. Tubular body with the mouth directed upwards & surrounded by tentacles

4. Attach to substratum by pedal disc

5. Reproduce asexually by budding, fission, or pedal laceration

Medusa Body Plan of a Cnidarian

1. Bell or umbrella-shaped

2. Usually free-swimming

3. Mouth directed downward

4. Tentacles may extend down from the rim of the umbrella

Nerve Net

In the gastodermis & the epidermis layer

Class Hydrozoa (Phylum Cnidaria) Characteristics

1. Most are marine with both polyp & medusa forms

2. Hydra 2a. Polyp stage dominant 2b. Bottom end has a basal or pedal disc for attachment 2c. the hypostome: the mouth (oral end) on a conical elevation 2d. Ring of 6-10 hollow tentacles with cnidocytes encircling the mouth

3. Medusa contains Velum (shelf)

4. Hydras reproduce sexually & asexually

   1. Asexual Reproduction: Budding

5. Most hydra medusa are dioecious

Class Scyphozoa (Phylum Cnidaria) Characteristics

1. Most of the larger jellyfishes belong in class

2. Medusa is the dominant stage

3. Nearly all float in the open sea

4. Bell varies in shape & sizes 4a. Composed mostly of mesoglea

5. Lack shelf-like velum found in hydrozoan medusae

6. Mouth located beneath the umbrella

7. Manubrium forms 4 oral arms

8. Tentacles, manubrium, & often the entire body may have nematocysts

9. 4 gastric pouches lined with nematocysts connect with the stomach

Which class do most of the larger jellyfish belong to?

Class Scyphozoa

Dominant stage of Scyphozoan jellyfish

Medusa

Class Scyhozoa Reproduction & Development

1. Sexes are separate

2. Fertilization is internal in the gastric pouch of the female; sperm is carried to gastric pouches 3.Zygote develops into a ciliated planula larva 3a.Attaches & develops into a scyphistoma

3. Schyphistoma undergoes strobilation 4a: Strobilation: Forms buds called ephyrae that break loose to form jellyfish medusae

The zygote of scyphozoans (cnidarians) develops into...

ciliated planula larva -free-swimming or crawling larva

what do planula larva attach & develop into?

Scyphistoma -the fixed polyplike stage in the life cycle of a jellyfish

Scyhistoma (scyphozoans) undergoes what process?

Strobilation -asexual reproduction; forms buds called ephyrae that break loose to form jellyfish medusae

ephyrae

Buds that break loose to form jellyfish medusae (immature medusae)

Class Cubozoa "Box Jelly," (Phylum Cnidaria) Characteristics

1. Medusa form is dominant

2. Polyp is inconspicuous or unknown

3. Umbrella is square (box-like) 3a. One or more tentacles extend from each corner

4. At base of each tentacle is a flat blade called a pendulum

5. Strong, fast swimmers

6. Highly venomous

7. Feed mostly on fish in nearshore areas

8. The sea wasp 8a. Off the coast of northern Australia can lead to respiratory failure, cardiac arrest, & death within minutes

Class Anthozoa (cnidaria) Characteristics

1. Flower animals: polyps are the dominant stage

2. Lack a medusa stage

3. All marine

4. Large gastrovascular cavity

5. No special organs or respiration or excretion

6. Sea anemones & corals

Dominant stage of anthozoans (cnidarians)

Polyps

Sea Anemones (anthozoans) Characteristics

1. Polyps are larger & heavier than hydrozoan polyps

2. Attach to shells, rock, timber, etc by pedal discs. Some burrow in mud or sand

3. Carnivorous

4. Crown of tentacles surrounds the flat oral disc

5. Slit-shaped mouth leads into a pharynx

6. Gastrovascular cavity is divided into 6 pairs of primary septa or mesenteries (tissues)

7. When in danger, water is rapidly expelled through pores as the anemone contracts to a smaller size

Sea anemone pharynx

the muscular part of the digestive system that serves to ingest as well as egest food

Sea anemone gastrovascular cavity

Divided into 6 pairs of primary septa or mesenteries (tissues)