The Invertebrates – Arthropoda
Arthropod = ‘jointed legs’
, Ecdysozoa:
An exoskeleton is a firm, non-living covering that provides an animal with both
protection and support.
To grow, they shed the old exoskeleton and expand and harden a new, larger one.
Moulting probably evolved only once during animal evolution.
Some ecdysozoans have worm-like bodies covered by thick and flexible exoskeleton
called cuticle.
A thin cuticle allows the exchange of gases, water, etc. but restricts the animal to life
in water.
Phylum Onychophora: (e.g. Peripatus)
Once thought that they were the missing link between annelids and arthropods – not
true.
Old (up until 1990s) idea of ‘Articulata’ now discredited.
Moulting, chitinous cuticle (arthropod features).
Soft, fleshy non-jointed appendages, nephridia (annelid features).
Phylum Tardigrada: ‘Water Bears’
0.05 - 1.2mm
1000 species
Anabiotic
Can dry or freeze
+150 to -272.8oC
X-rays of 570,000 rads (500 kills us)
Vacuum or high pressure
Found everywhere
Arthropod = ‘jointed legs’
, Ecdysozoa:
An exoskeleton is a firm, non-living covering that provides an animal with both
protection and support.
To grow, they shed the old exoskeleton and expand and harden a new, larger one.
Moulting probably evolved only once during animal evolution.
Some ecdysozoans have worm-like bodies covered by thick and flexible exoskeleton
called cuticle.
A thin cuticle allows the exchange of gases, water, etc. but restricts the animal to life
in water.
Phylum Onychophora: (e.g. Peripatus)
Once thought that they were the missing link between annelids and arthropods – not
true.
Old (up until 1990s) idea of ‘Articulata’ now discredited.
Moulting, chitinous cuticle (arthropod features).
Soft, fleshy non-jointed appendages, nephridia (annelid features).
Phylum Tardigrada: ‘Water Bears’
0.05 - 1.2mm
1000 species
Anabiotic
Can dry or freeze
+150 to -272.8oC
X-rays of 570,000 rads (500 kills us)
Vacuum or high pressure
Found everywhere
