Lecture 16- Australian invertebrates' diversity

Question 1

What are the 6 terrestrial invertebrate phyla?

Answer 1

1. Platyhelminthes: flatworms 2.Nematoda: roundworms 3.Annelida: segmented worms 4.Arthropoda: insects etc 5.Onychophora: velvet worms 6.Mollusca: snails etc -invertebrates are the most species rich part of the animal kingdom, and most abundant -possibly 90% of world species

Question 2

What do Platyhelminthes look like?

Answer 2

• bilateral symmetry
• eye spots (light sensory)
• dorso ventrally flattened in transverse section

Question 3

What are the two main types of Platyhelminthes?

Answer 3

1. Free living: e.g. brown striped flatworm, some flatworms are brightly coloured, most quite small constrained to small size 2. Parasitic: e.g. tapeworm from vertebrate digestive tract, often quite well develop interaction, some have complex life cycles, even more hosts

Question 4

What do Nematoda look like and what are their characteristics?

Answer 4

-large groups -(roundworms):

some free-living, mostly parasitic

• e.g. in kangaroo gut, non harmful to the animal
• extremely sophisticated!

Question 5

What do annelida look like and what are their characteristics?

Answer 5

• segmented worms, like earthworms for example
• metamorphic segmentation, both on the inside and outside
• more complex body structure
• some grow very big:Giant Gippsland Earthworm up to 3m long!!!
• leeches: parasitic -also many in marine environment -e.g. rainforest groups: turquoise earthworm

Question 6

What are the key unifying characteristics of arthropoda?

Answer 6

-largest invertebrate group in terrestrial systems 1. exoskeleton (external) & 2. jointed legs -

Question 7

What are the characteristics of subphylum of Arthropoda the Chelicerate?

Answer 7

-(no antennae): spiders, mites, ticks & scorpions -very abundant group, 39000 species of spiders in Australia alone

Question 8

What are the characteristics of spiders?

Answer 8

-many are active hunters and have venom to subdue or kill their prey, have fangs (inject the venom) -or have webs - some sp. exhibit maternal care: female carrying her young (e.g Wolf spider)

Question 9

What are the characteristics of scorpions?

Answer 9

-some are active hunters, some wait and then attack -in the arid zone -sting in their tail -also in rainforests

Question 10

What are the characteristics of subphylum of Arthropoda the Crustacea?

Answer 10

-2 pair antennae branched legs e.g. crabs, slater (pill bug) etc -most are marine

Question 11

What are the characteristics of subphylum of Arthropoda the Myriapoda?

Answer 11

-1 pair antennae centipedes, millipedes -myriapods= many legs

Question 12

What are the characteristics of subphylum of Arthropoda the Hexapoda?

Answer 12

-insects: butterflies, moths, ants, beetles etc. amazing diversity in morphology & ecology -good for experiments, as cheap, can manipulate, can have many in an experiment

Question 13

What is the value of invertebrate models in connection to climate and species distribution?

Answer 13

-Common Brown Butterfly -distribution: correlates with winter rainfalls and milder temperature -

Question 14

What is the life cycle of Common Brown Butterfly?

Answer 14

-tiny larvae and eggs probably most susceptible to dryness and heat -project to test this -and yes highly susceptible to desiccation and heat, so can’t adapt quickly

Question 15

How was the experiment with butterflies done?

Answer 15

• Portable weather- station: macroclimate data (air temp, rainfall, wind-speed etc.) Air temp • measured Computer programs: reconstruct microclimate from macroclimate data • Data-loggers: temp & humidity in grass tussocks (sun/shade) -this was to confirm the lab results, and yes!

Question 16

What are characteristics of the Phylum Onychophora?

Answer 16

-(velvet worms) early lineage links to arthropods -closer related to arthropods than to worms

Question 17

What are characteristics of the Phylum Mollusca?

Answer 17

-huge group in marine environments -snails etc.

Question 18

What are the fossils of invertebrates found in SA?

Answer 18

-Invertebrate fossils in SA: 600MY -also Jurassic dragonfly (approx 190MY) -have quite a few fossils in Australia -dragonflies still have the same body plan

Question 19

What are the origins of Australia invertebrate faun?

Answer 19

1. Gondwanan groups e.g. freshwater worms 2. Asian elements e.g. bird eating spiders 3. Archaic element: descendants of widespread Pangean (when world was Pangea) groups, primitive cockroaches, scorpion flies, velvet worms

Question 20

What are some more characteristics of Onychophora (velvet worms)?

Answer 20

-up until DNA studies not many species 70 worldwide, with DNA testing 40 more genera and only in Australia have 40 species -all of them have similar body plan, similar habitat so *Allozyme (allele codes for particular enzyme or proteins= can inform us about population relations) studies on Euperipatoides leukartii: more species including E. rowelli * Euperipatoides rowelli mtDNA & micro satellite studies: found a # of divergent groups! -habitat: woods

Question 21

What was the study with velvet worms?

Answer 21

-velvet worms live in wet environment often, rotting log -habitats are small, many geographical barriers on a small scale -have area with one species and another one with another species, the overlapping zone= should have hybrid babies with defects, -the species vary by 20% in their DNA! a lot! -Birth defects in a velvet worm due to “out-breeding depression” (this is due to 2 distinct species interbreeding) low fertility & 5% of young have birth defects, e.g. missing legs -the hybrid zones supported the DNA results

Question 22

How does reproduction work in velvet worms?

Answer 22

• not romantic
• male comes along, puts sperm on the body of female, there her body will break down and the sperm will get into the reproductive system of the female
• can have up to 25 embryos in her, at different development stages, this is as she can control when the sperm starts developing
• tested for paternity, multiple fathers!

= mate selection! maximum change for offspring success