Invertebrates Flashcards
How many roundworms are there thought to be?
1 million but 25000 known
What are the features of roundworms?
Bilateral symmetry
Cylindrical body with tapered end
Are internal organs in round worm surrounded by mesoderm?
No so they are psedocoelomate
What is the purpose of multi layered cuticle?
Helps maintain high pressure
Are the muscles in the round worm antagonistic?
No
How do muscles in the round worm work?
They twitch side to side and the hydrostatic skeleton pills them into shape
What is the scientific name for round work?
Nematoda
What is the lifestyle like for free living round worm?
Marine freshwater terrestrial
All habitats dessert to polar region
Feed on bacteria
Microscopic organisms
What is an important of free living round worms in the soil?
Important in soil nutrient cycling
What are the two lifestyles of roundworms?
Free living
Parasites of animals
What is elephantiasis caused by?
Infection with filariasis type nematodes which infects lymphatic system
How do roundworm reproduce?
Sexual reproduction- internal fertilisation
Are roundworm mainly dioecious (mainly male or female)?
Yes
What was the first multicellular organisms to have its genome sequenced?
Caenorhabditis elegans
What are examples of the phylum Echinodermata?
Sea lilies
Sea urchins
Star fish
Sea cucumbers
What are features of Echinodermata?
All marine, bilateral symmetry in larvae but 5 fold radial symmetry in adults, coelomates
What is the body plan of Echinodermata?
Water vascular system and thin epidermis covering a endoskeleton and external spines
How to Echinodermata reproduce?
Sexual reproduction with separate sexes
How many species are Echinodermata?
7000
What are the features of the phylum Mollusca?
Eg snails, clams, octopuses
Bilateral symmetry
Muscular foot
Well developed head
What are features of the class Bivalvia?
Aquatic animals with two shell valves
Sedentary or burrowing
Expanded gills for filter feeding
Separate sexes
What is torsion?
Twisting of the body in relation to head and foot brings anus above the head
What is a Ctenidia?
Gill
What are features of the class Gastropoda?
Well developed head
Assymmetrical body
Herbivorous or carnivorous
Separate sexes or hermaphrodite
Do snails have both both genitalia?
Yes
How do snails mate?
Slow ritual where sperm and a love dart (mucus covered calcareous dart) is exchanged
Are love darts a secondary sexual characteristic?
Yes
What are features of the class Cephalopoda?
Marine predator Interanal shell Eg squid Brain in braincase Courtship between separate sexes
What are features of the phylum Annelida?
Eg fan worms, earthworm
Bilateral symmetry
Body covered in chaetae (bristles used for movement)
What are advantages of coelomate body plan?
Hydrostatic skeleton
Transport of excretory and sexual products
What are advantages of Metameric segmentation?
Allow independent movement of different of muscles
What are advantages of a body covered with chaetae?
Bristles help with movement
What are features of errantia?
On sea floor
Well defined jaw and eyes
Body segment with prominent parapodia
sexual reproduction
What are features of sedentaria?
Earthworms are burrowers
Leeches are ectoparasites or predators
Hermaphrodites
Regeneration
