Animals Lec 23-26: Porifera, Cnidarians, Eumetazoa,Platyhelinthes, Annelids, Nematodes, & Arthropods

Question 1

what makes an animal, an animal?

Answer 1

Blastula reproduction
Shared cytological and biochemical features (collegen), certain extracellular matrix and cell adhesion molecules
Multicellular
Heterotrophic
Distinct cell types (nerves)

Question 2

what are the characteristics of Porifera?

Answer 2

Lack true tissues

ingestion from choanocytes

digestions from amoebocytes

spicules hold the sponge together
multicellular NOT colonial

have flattening and branching of their bodies to increase SA

Heterotrophic and get food through water circulation through body

reproduction via blastula and gastrula. and massive explosion of sperm into the water which is filtered through other sponges and taken to the ovum

Question 3

characteristics of Eumetazoa?

Answer 3

carnivores
named after their stinging cells used for feeding and defense (found on tentacles)

digestive enzymes released from glad cells, enzymes break down food into particles whcih are then engulfed

radial symmetry - always symmetrical

diploblastic - 2 cell layers with mesoglea

Question 4

What are the advantages of multicellularity?

Answer 4

Specialisation of cells - helps efficiency

Can grow - allows motility, protection from predation, and more efficient reproduction and food collection.

Question 5

challenges of multicellularity?

Answer 5

Reduced SA - efficiency of processing that allows exchange with the environment. SA influences effectiveness of uptake of nutrients and gas exchange.

Metabolism takes place in volume of biomass

Requires many small cells that can interact instead of large cells.

Question 6

Explain the heterotrophic feeding habits of sponges through te 4 digestion steps:

Answer 6

Ingestion - filter feeding (mainly for sponges), bulk feeding, substrate (paraistes - they eat the host they are in), and fluid feeding (misquitos.

Digestion - breakdown of food
either mechanically or chemically
(can be extracellular or intracellular)

Absorption - uptake of nutrient molecules

Elimination - removal of undigested molecules

Question 7

Explain multicellularity vs colonial cells in animals

Answer 7

Multicellular - organisms composed of many cells that are integrated and interdependent with specialized tissues and organs (if a cell is separated from colony, it dies)

Colonial cells - aggregations of mostly independent, identical cells (can survive if separated from the colony)

Question 8

What are choanocytes? And what do they do?

Answer 8

They are flagellated cells that line the sporangcoel of a sponge. Choanocytes create a current draeing water in

Movement of choanocytes flagellum draws water through the collae of projections. Food particles trapped in the projections mucus coats are engulfed by phagocytosis and either digested or transfered to ameobocytes

Question 9

Waht are the advantages of Bilateral symmetry?

Answer 9

Streamlined body shape - directional movement to easily move in chosen direction

Cephalization - sensory organs concentrated in front (on head) for better stimuli response

Enhances mobility and thus resource seeking

Allow for redundancy, coordination of organs and movements, efficient motility, and guts and organs

Question 10

Explain the ectoderm and what it turns into

Answer 10

Ectoderm: outer covering of body and in some animals the nervous system

Epidermis, sweat glands, hair follicles. Epithelial lining of mouth and rectum, sensory receptors in epidermis. Eyes, nervous system, adrenal medulla, tooth enamel, and epithelium of pituitary gland.

Question 11

Explain the mesoderm and what it turns into:

Answer 11

Mesoderm: layer between ectoderm and endoderm (forms muscles and most other organs)

Question 12

Explain the endoderm and what it turns into:

Answer 12

Endoderm: lines digestive tube (liver and lungs in vertebrates) -

Question 13

What is a coelomate?

Answer 13

animals with “true coelom”

body cavity completely lined with mesoderm (earthworms)

Question 14

waht is coelom

Answer 14

another name for the body cavity formed from mesoderm tissue. Inner and outer layers of tissue surrounding cavity connect and form structures that suspend the internal organs (animals with true coelom are called Coelomates) - e.g. earthworms

Question 15

What is a pseudocoelom?

Answer 15

a cavity that is formed from both mesoderm and endoderm (e.g. roundworms)

Question 16

waht is an acoelomate?

Answer 16

no body cavity (flatworms - platyhelminthes)

Question 17

What are the 5 advantages of coelom?

Answer 17

Support - provides hydrostatic skeleton to support body and organs

Protection - of internal organs from injury and infection

Nutrient transport - coelomic fluid helps transport nutrients and oxygen to body’s tissue

Waste removal - coelomic fluid helps remove waste products from body

Reproduction - coelom provides space for development of gametes and embryos.

Question 18

What are platyhelinthes? explain their habitats, their body form, and tissue type (diploblastic or triploblastic)

Answer 18

Platyhelminthes (flatworms):

ubiquitous, in most habitats, free-living, parasitic (including flukes and tapeworms), thin bodies, and range from microscopic to macroscopic

Body form - flat, long, have nervous tissue and gastrovascular tissues.
Anterior sensory concentration, dorsally flattened, chemosensors, maximised surface area to volume ration

Triploblastic - have an ecto, endo, and mesoderm

Question 19

What are annelids? explain their body type and shape, and their habitats:

Answer 19

Annelids (segmented worms and leeches): aquatic habitats

coelomates and segmented. Metamerism, Head region, segmented trunk and post-segmental tail, parapodium, coelom, and organ system.

Question 20

What is metamerism?

Answer 20

Metamerism - segmentation of animal body into series of repeating similar segments called metameres or somites.

Question 21

What are nematodes? What is their habitat, their body shape and systems?

Answer 21

Nematodes (roundworms): aquatic, live in wet soils and body fluids.

Nonsegmented, pseudocoelomate, very diverse. Have complete gut, ridged cuticle that is shed during growth.

no circulatory system, and usually sexually reproduce

Question 22

Explain the phylogeny of Plathelminthes, Annelids, and Nematodes:

Answer 22

Each phyla is a Protostomia. Platyhelminthes and Annelids are Lophortrochozoa. Nematode is Ecdysozoa

Question 23

What external features do arthropods share?

Answer 23

Bilateral symmetry

Metameric segmentation - body segmented internally and externally. Septa may be reduced, and segments may be fused and highly modified. Consist of head, thorax, and abdomen

Exoskeleton

Appendages (segmented, jointed, and specialised) - can create large amounts of diversity by changing the number of repeating segments and the genetic programs for building structures (Hox genes)

Question 24

Why is metameric segmentation advantageous?

Answer 24

More efficient locomotion, utilizing localized changes in body shape and hydrostatic pressure. Protects body from injury. Divides segments into specific function (tagmatisation)

Question 25

Explain Hox genes?

Answer 25

Hox genes - specify how structures develop in different segments of body

Question 26

What internal features do arthropods share?

Answer 26

Coelom Open circulatory system - haemolymph pumped into interconnected body cavities where body cells are surrounded by fluid, dorsal blood vessels and prospect

Question 27

Where do arthropods fit in the animal phylogeny?

Answer 27

Part of Protostomia, particularly an Ecdysozoa - all have a cuticle, which forms the exoskeleton. All phyla within this group moult their exoskeleton (ecdysis)

Question 28

What are the 5 subphyla of Arthropods?

Answer 28

Hexapoda - insects and collembola Crustacea - decapoda, barnacles, and copepods Myriapoda - centipede and millipede Chelicerata - spiders, scorpions, horseshoe crabs Trilobite - extinct subphyla

Question 29

compare the environment of water to air:

Answer 29

Water More dense than air Water More viscous than air Higher gas concentration of oxygen in air Conductivity of light and sound Stability - water more stable temperature, substrate, and current wise

Question 30

What is an exoskeleton and waht is the function of the Exoskeleton?

Answer 30

Exoskeleton - cuticular exoskeleton (epicuticle, exocuticle, endocuticle, epidermis, and hair structures). external “bones” with muscles on inside (arthropods). Muscle flexation connects to each separate part - the opposite of endoskeleton muscle system. Structure: outer waxy layer, water resistant over chitinous horns and flexible layers, formed from epidermis. Function: support movement and protection (desiccation and predation) includes jointed and flight appendages

Question 31

What are the exoskeleton's limitations?

Answer 31

Limitation: limits growth and exoskeleton is heavy in bulk. Arthropods grow through ecdysis. The new cuticle is soft and the animal is vulnerable. With punctuated growth over time.

Question 32

What are the other skeleton types?

Answer 32

Hydrostatic - fluid filled cavity under hydrostatic pressure. Muscles produce pressure of fluid (cnidaria). Exoskeleton - external “bones” with muscles on inside (arthropods). Muscle flexation connects to each separate part - the opposite of endoskeleton muscle system. Endoskeleton - internal skeleton with muscles outside (humans)

Question 33

What are the three types of metamorphosis?

Answer 33

Ametabolous - don’t have big changes, with slow gradual ecdysis Hemimetabolous - each step gets slowly more adult features (locusts) Holometabolous - full change and likely change in niche, feeding, locomotion, etc. - butterflies.

Question 34

What are the two types of appendages in arthropods

Answer 34

Uniramous - series of segments attached from end-to-end (insects) Biramous - branches into 2, each branch is a series of segments attached end-to-end (e.g crustacean limbs)

Question 35

What are the advantages of flight in arthropods

Answer 35

higher locomotion in air, uses less energy. Flight insects access new niches, evolved from existing appendages. Advantages - easier escape, easier access to food and mates, and new locations Direct flight Vs indirect flight

Question 36

What is a trachea?

Answer 36

infolding of ectoderm, look like silvery network branches that carry O2 to cells and CO2 away with holes where air comes in through (spiracles) - every cell is connected to tracheal network

Question 37

What are gills?

Answer 37

organs for gas exchange - inside carapace, part of biramous appendage, branching

Question 38

What are book gills?

Answer 38

type of organ for gas exchange - sit outside exoskeleton, origin of modified appendages

Question 39

What are book lungs?

Answer 39

consist of atrium or hollow pouch with a series of internal leaves that lie above one another. Highly vascular, inside exoskeleton, and in terrestrial animals

Question 40

How does respiratory media affect gas excahnge? What must a gas exchange organ look like?

Answer 40

Respiratory media affects gas exchange efficiency as substances must be dissolved in aqueous solutions, and the amount of exchange needs to be proportional to the surface area. Organ surfaces must be large and thin enough for gas exchange.

Question 41

What are the two main reasons reproduction is affected by the environment?

Answer 41

Variability of environment affects fertilisation success and survival of offspring (use nests to protect offspring) Marine species require specific needs of the environment, not met in terrestrial environments. Required species to adapt to develop diverse behaviours to allow terrestrial species