Lecture 12 Flashcards
What three groups of ecdysozoans are worm like marine animals?
Priapulids
Kinorhynchs
Loriciferans
What are priapulids?
Unsegmented, three part body plan, burrow in soft sediment marine animals
What do priapulids eat?
Soft body invertebrates such as polycheates
How do priapulids eat?
Capture prey with a toothed, muscular parynx that is everted through their mouth
What are kinorhynchs?
Microscopic marine animals that live in marine sands and muds
How many segments are kinorhynchs bodies divided into?
13- each with a separate cuticular plate
What happens to the cuticular plates of each segment of kinorhynchs as they grow?
They are periodically molted
How do kinorhynchs feed?
Ingesting sediment through their retractable proboscis, digesting organic matter
What are loriciferans?
Small animals less than 1mm
What is the structure of loriciferans bodies?
Divided into head, neck, thorax, abdomen, covered in 6 plates
Where do loriciferans live?
Course marine sediments
What do loriciferans eat?
Not much is known, but some eat bacteria.
What are horsehair worms?
Very thin, upto 2m long, freshwater worms
What are horsehair worm larvae?
Internal parasites of insects and crayfish
How do horsehair worms feed?
Many feed only as larvae
Others grow and moult by absorbing nutrients from the environment
Adult has no mouth and reduced nonfunctional gut
What gives the unsegmented body of nematodes its shape?
A thick, multilayerd cuticle
How many times does a nematode shed its cuticle?
4 times
How do nematodes exchange oxygen and nutrients with their environment?
Through their cuticle and the gut
How are materials moved through the gut of nematodes?
Rhythmic contraction of a highly muscular organ called the pharynx at the anterior end
How do nematodes move?
By contracting their longitudinal muscles
What soil inhabiting nematode is used as a model organism in labs?
Caenorhabitis elegans
Why is Caneorhabitis elegans used as a model organism?
Because it is easy to cultivate, matures quickly and has a fixed number of body cells, its genome has been mapped.
What do nematodes eat?
Many are predators- feed on protists and other small animals such as roundworms
What diseases do nematodes cause in humans?
Trichinosis, filariasis, elephantiasis
What do arthropods all have?
Limb like appendages
What are some features of arthropods that made them successful?
Segmented bodies
Muscles attached to the inside of rigid exoskeletons
Segments have muscles and jointed appendages
What do jointed appendages do?
Permit complex movement
Specialized for different functions
What does encasement within an exoskeleton do?
Provide the animal with support for walking, protection from predators.
How do arthropods not dry out in dry air?
Chitin provides waterproofing
What are 4 major arthropod groups?
Crustaeceans, hexapods, myriapods, chelicerates
Arthropods constitute a ________ group
Monophyletic
What group was debated to be more closely related to annelids or arthropods?
Onychophorans (velvet worms)
More close to arthropods
Where do onychophorans live?
Leaf litter in humid, tropical environments
What bodies to onychophorans have?
Soft, segmented, covered in thin flexible cuticle containing chitin
What are water bears called?
Tardigrades
What bodies to tardigrades have?
Fleshy, unjointed legs
Fluid filled body cavities are hydrostatic skeletons
Where do tardigrades live?
Marine sands
Temporary water films on plants
Where did jointed legs first appear?
Trilobites- disappeared in the great permian extinction
What are the dominant marine arthropods today?
Crustaeceans
Name some crustaceans.
Shrimps, lobsters, crayfishes, crabs (decapods)
Sow bugs (isopods)
Copepods
What are some unusual crustaceans that are sessile as adults?
Barnacles
What are the 3 main regions of a crustaceans body?
Head
thorax
abdomen
How many appendages do crustaceans head bear?
5 pairs
What is the name of a fold of exoskeleton in some crustacean species that extends dorsally and laterally back from the head to cover and protect some segments?
The carapace
What happens to ferilized eggs of crustaceans?
They are attached to the outside of the females body during early development
What name is given to crustacean larvae?
Nauplius
How many eyes and appendages do crustacean larvae have?
One eye
3 pairs of appendages
What are insects?
6 legged hexapods
What regions of body do insects have?
Head, thorax, abdomen
What are some features of insects?
Gas exchange system made from trachea and spiracles
Single pair of antennae on the head
Three pairs of legs attached to thorax
How are insects different to other arthropods?
They have no appendages from their abdominal segments
Who decided there are more insects?
Terry Erwin
What did terry erwin do?
Sample beetles in the canopies of a single rainforest tree, Lueha seemanni
What are wingless relatives of insects called?
Springtails, two-pronged bristletails and proturans
How can insects be distinguished from other hexapods?
External mouthparts and paired antennae that contain a sensory receptor
What name is given to the sensory receptor in the antennae of insects?
Johnston’s organ
What name is given to immature stages between moults of pterygote insects?
instars
What type of metamorphosis do butterflies have?
Complete metamorphosis
What is another type of metamorphosis?
incomplete metamorphosis- where changes are gradual
What name is given to the specialized phase in which a caterpillar transforms to a butterfly?
pupa
What insects were the first animals to achieve the ability to fly?
Pterygote insects
How did flight cause the unparalleled evolutionary success of insects?
New lifestyles opened up, feeding opportunities only insects could exploit
What wings do most adult flying insects have?
2 pairs of stiff, membranous wings attatched to the thorax
What wings do true flies have?
Just one pair
What wings to beetles have?
Forewings are heavy, hardened wing covers
What two groups of pterygote insects cannot fold their wings back against their bodies?
Mayflies
Dragonflies
This is the ancestral condition
What name is given to all other pterygote insects that can fold their wings against their bodies?
Neopterans
How do many neopteran groups acquire adult organ systems such as wings and compound eyes?
Gradually, through several juvenile instars
What is a new major group of neopterans?
Mantophasmatodeans- described in 2002
What subgroup of neopterans has complete metamorphosis?
Holometabolus neopterans
How does the time at which insects separated from the lineage leading to current crustaceans lead to their success?
hexapods penetrated an environment that lacked other similar organisms
What evidence suggests that insect wings evolved from a dorsal branch of a crustacean-like limb?
Homologous genes control development of insect wings and crustacean appendages
What two body regions do myriapods have?
A head and a trunk
What do centipedes and millipedes have?
head
long, segmented flexible trunk with many pairs of legs
How many pairs of legs to centipedes have per segment?
one pair
What do centipedes eat?
Prey on insects and other small animals
How many pairs of legs do millipedes have per body segment?
2 pairs
What do millipedes eat?
They scavange and eat plants
How many pairs of legs do chelicerates have?
4 pairs
What are the three clades of chelicerates?
Pycnogonoids
Horseshoe crabs
Arachnids
What are pycnogonoids?
Sea spiders, some eat algae, most are carnivorous
How many living species of horseshoe crab are there?
4
Where are horseshoe crabs common?
Shallow waters along eastern coasts of North America and southern and eastern coasts of Asia
What disease are mites vectors for?
Rye mosaic disease- cause mange in domestic animals and skin irritation in humans
What 6 factors effected diversity of protostome evolution?
Segmentation Complex life cycles Parasitism Diverse feeding structures Predation locomotion
