Lecture 6 DA Flashcards
Which subphyla of arthropoda is the 2nd largest?
Chelicerata.
What percentage do arachnids make up chelicerata?
98%.
Do chelicerata have antennae?
No.
Do chelicerata have mandibles?
No.
How many tagmata do chelicerata have?
2, a cephalothorax called prosoma, and abdomen called opisthosoma.
How many uniramous appendages do chelicerata have, and what are they called and used for?
Chelicerae - used for handling food, are fangs in spiders.
Pedipalps - Are like chelicerae, used to handle food.
4 pairs of walking legs.
What are book gills, and where are they found?
They are flap-like gills in the opisthosoma. Some are external, some are internal.
Internal ones are called book lungs.
What are the three classes of chelicerata?
Merostomata
Arachnida
Pyncogonida
What are merostomata known as, and how many species?
Made of 4 species, the horseshoe crabs.
What is the largest class in chelicerata?
Arachnida.
What are the four important orders of arachnida?
Araneae - true spiders
Opiliones
Scorpionida
Acari
What kind of environment do arachnida live in?
All terrestrial.
Are the arachnida cuticle waxy or calcareous?
waxy.
What do arachnida use to breathe?
Book lungs.
Can tracheae of arachnida be closed?
Yes.
How do arachnida excrete, and what does this aid in?
Malpighian tubules, aids against water loss.
Where does fertilisation occur in arachnida?
Internal.
What is the structure of arachnida zygotes?
They are shelled.
What do mechanoreceptors do in arachnida?
Detect air vibrations.
What chelicerae adaptation do aranae have?
Fangs for stabbing and tearing prey. Usually has a toxin gland.
How do aranae digest food?
Externally, due to no mandibles.
Vomit digestive enzymes to dissolve, then suck.
How many pairs of eyes do aranae have?
4.
How do aranae spin webs?
Spinnerets.
Where are most of the internal organs of aranae found?
Opisthosoma.
What is the opisthosoma of aranae made of?
Several fused segments, which isnt visible externally.
What is the pedicel of aranae, and what is its purpose?
Is the junction between prosoma and opisthosoma. Used for flexibility and placing silk, a feature of true spiders.
Do aranae abdomens have any leg appendages?
No.
What is spider silk?
Complex liquid crystalline polymer that becomes solid when stretched. Equivalent to steel in cross sectional area.
How many glands produce silk in aranae?
7 types, each make a different kind.
How are spider silk glands arranged? How are these further arranged?
Glands are arranged in spools. The spools are arranged in spinnerets.
What are the functions of spider silk (6)?
- Used for locomotion - dragline.
- Travelling - ballooning.
- Stationary webs made of a strong non-sticky framework, covered in sticky webbing.
- Used in feeding by wrapping prey.
- Used in reproduction, wrapping food as offering, transferring sperm etc.
- Egg cocoons.
What is the order opiliones?
Called daddy-long legs, which also incorrectly refers to the cellar spider, and is a true spider.
Real daddy-long legs arent true spiders.
What is the the largest living arachnid?
Scorpionida - scorpions.
Where do scorpionida live?
Arid or humid climates.
What modified appendages do scorpionida have (2)?
Large pedipalps with chelicerae.
Telson with a stinger.
How do scorpionida catch prey?
They use mechanoreceptors to detect air vibrations.
What are the order acari?
Ticks/mites
What are the tagmata of acari like?
Cephalothorax and abdomen are fused.
What is the difference between a tick and a mite?
-Tick
Larger, more triangular/rounded
Bloodsucking parasites that anchors to the host, and transmits parasites.
-Mites
Longer mouthpart, more diverse
Can be freeliving or parasitic, aquatic or terrestrial.
What are the chelicerata class pycogonida?
Sea spiders.
What are the tagmata of pycogonida like?
Mostly cephalothorax, with a reduced absomen. Look like daddy-long legs.
Where is the chelicerae of pycogonida found?
Held by an elongated probuscus extending from its anterior end.
What are uniramous appendages believed to be a consequence of?
Convergent evolution.
What suggests crustaceans and hexapods are related?
The hox genes.
What are hox genes?
Genes responsible for developmental regulators.
How can we know the functions of hox genes?
By introducing mutations into them and observing the effects.
What common appendages are controlled by hox genes (3)?
Leg development, as well as wing placement and numbers.
What is an advantage of the hox genes?
Allows easier evolution and developmental adaptation, and addresses the diversity of arthropoda.
What did key adaptations for terrestrial life evolve from?
Biramous appendages.
What is an advantage of serial repetition?
Allows specialisation by modifying structures in certain regions, making specialised tagmata.
Are hox genes found in phyla that arent bilaterally symmetrical?
Yes.
Are vertebrates segmented?
Yes.
How do phylum onychophora catch prey?
Using sticky glands.
What feature do onychophora have in common with both annelids and arthropods?
Segmented coelomate protostomes.
What features do onychophora have in common with annelids only (3)?
Soft, non-calcified cuticle
Homonomous metamerism
Paired appendages
What features do onychophora have in common with arthropods only (3)?
Molting cuticle
Reduced abdomen
Have tracheae
What 3 phyla is the superphylum lophotrochozoa made of?
Ectoprocta
Phoronida
Brachiopoda
What do phyla within the superphylum lophotrochozoa have in common?
They share a structure called a lopophore, which is a ring of tentacles, O or U shaped, and used for suspension feeding. Water is drawn across, and cilia capture food. Also used for gas exchange.
Is the superphylum lophotrchozoa triploblastic? Do they have a complete gut? Are they coelomates?
They are coelomates, with a complete gut.
They are triploblastic.
Are lophotrochozoa cephalised?
No.
Where do lophotrochozoans live?
Almost entirely marine, on the bottom and sedentary.
Some ectoprocta are freshwater.
What do lophotrochozoans secrete?
Protective covering.
What are phylum ectoprocta like?
Is a single polypide, living in a zooecium, a protective covering.
How does an ectoprocta extend its locophore?
An orifice in the zooecium allows an introvert to extend it.
Do ectoprocta have an operculum and funiculus?
Yes.
What do ectoprocta look like?
Look like colonial coral, are all clones of each other.
What muscles are used to extend and retract the introvert in ectoprocta?
Circular to extend it, and retractor muscles to retract.
Aside from muscle action, how else can ectorpocta extend its locophore?
Can have a membrane that it pulls on to increase intra-pressure to force it out.
Do ectoprocta have polymorphism in its colony?
Yes.
What are feeding ectoprocta called?
What about reproductive and defensive?
Feeding - autozooids
Reproductive - ovicells
Defensive - avicularium and vibraculum
Where do phylum phoronida live?
2 genera that live entirely marine.
What are phylum phoronida?
Solitary worms.
How do phylum phoronida protect themselves?
Chitinous protective covering.
Are phylum phoronida sedenrary?
Yes, in sediment.
Do phornidia have metanephrida and a blood circulatory system?
Yes.
Where do phylum brachiopoda live?
All marine.
Are phylum brachiopoda solitary?
Yes.
How do brachiopoda protect themselves?
Calcareous bivalve shell, dorsoventral side.
How do brachiopoda attach to substrata?
Pedicle.
Do brachiopoda have metanephridia and blood circulatory system?
Yes.
How do brachiopoda open and close its shell?
Has abductor and adductor muscles.
Is there any evidence that unites all the lophotrochozoans?
Only their locophore does. No other evidence suggests theyre related.
Are lophotrochozoans protostomes or deuterostomes?
They are believed to be protostomes.
Are phylum rotifer coelomates?
No, blastocoelomates.
What do phylum rotifera eat?
Graze on algae.
How do rotifera feed?
Feed with a corona.
What’s unusual about rotifera reproduction?
Some species have no males, where the females reproduce entirely by parthenogenesis.
Are phylum chaetognatha coelomates?
Yes.
What do chaetognatha eat?
Feed on marine plankton.
How do protostome coeloms develop?
By schizocoely.
What is schizocoely?
Coelom develops by the mesoderm splitting, with the cavity formed becoming the coelom.
How do deuterostome coeloms develop?
By enerocoely.
What is enterocoely?
Mesoderm forms in pockets from the gastrocoele, pinching off part of it (the gastrocoele) to form the coelom.
The coelom is therefore a remnant of the gastrocoele.
Is the coelom a remnant of the gastrocoele in schizocoely development?
No.
What kind of cleavage do deuterostomes have in their zygotes?
What about protostomes?
What kind of cleavage do locotrophozoans have?
Deuterostomes - radial
Protostomes - spiral
Locotrophozoans - spiral
