#24 terrestrial invertebrates diversity Flashcards
1
Q
what is the phylum Platyhelminths
what are their features
A
flatworms
- dorso-ventrally flattened - flat
- no circulatory system
- can be free living or parasitic
- parasitic flatworm is a tapeworm: which lives in the gut of host species
2
Q
what is the phylum nematoda
what are their features
A
roundworms
- cylindrical body
- some are free living, some are parasitic
- parasitic nematode can live in gut of kangaroo
3
Q
what is the phylum annelida
what are their features
A
segmented worms
- complex body structure
- have segmentation down the length of its body
- includes earthworms and leaches
- earthworms have a nervous system, they are hermaphroditic, important in nutrient recycling and soil health
- leaches are an ectoparasite - they don’t live in the host but need a host for food
4
Q
what is the phylum arthropoda
what are their features
A
insects
- largest group of terrestrial invertebrate
- most diverse group
- have an external exoskeleton and jointed legs
- i.e. spiders, scorpions, ticks, mites
5
Q
what is the phylum onychophora
what are their features
A
velvet worms
- have an exoskeleton
- old pangean group, have remained unchanged for a long time
- legs are fleshy and not jointed
- cannot disperse very well so speciation can occur
- studies have shown you can have two genetically different species of velvet worm living next to each other. not good at dispersing
6
Q
what is the phylum molluscs
what are their features
A
snails, slugs
- key feature is that they have a mantle
- thickened flat area on the back
- for snails mantle secretes a shell, but for slugs it doesn’t
- mantle used for respiration, excretion and sometimes feeding
7
Q
when are the oldest invertebrate fossils recorded?
A
around 600MYA
very long history of having invertebrates based on the fossil record
8
Q
what are archaic elements of invertebrates?
A
they are globally distributed groups - descendents from widespread pangea
includes cockroaches and velvet worms
