Lecture 15: Lophotrochozoa and Ecdysozoa Flashcards
Invertebrates
- Animals without a vertebra (backbone)
- All animals except for a portion of Chordata are invertebrates
- Vast majority of animals do not have these traits which are specific for vertebrates:
- Backbone
- Hinged jaws
- Limbs with digits
True or False: Chordata has some invertebrate members
True
All members of Eumetazoa have a
a digestive tract and differentiated tissues
* …aside from very select exceptions
Lophotrochozoa and Ecdysozoa have
Incredible diversity in shape and form
Huge mixture of __ and __ traits as they developed, got inherited and lost in different lineages of animals
homologous
analogous
- Difficult to use morphology to study ancestral relationship
Phylogeny of animals is based
on molecular evidence
Bilateria
animals with bilateral symmetry
Lophotrochozoa (exclusively invertebrate)
- Lophophore: crown of ciliated tentacles for feeding
- Trochophore larva: developmental stage which some animals of this group go through
- There are many Lophotrochozoans which do not show these traits
Ecdysozoa (exclusively invertebrate)
- Many members have cuticle exoskeletons for protection and support
- Moulting/ecdysis: Animals shedding its old exoskeleton to grow larger
Deuterostomia (some are vertebrates)
- Starfish
- Chordata, which include vertebrates
Lophotrochozoans examples
Incredible diversity, with the largest range of body forms within the group
* Flatworm, like a planaria
* Tapeworm
* Mollusca: snails, slugs, oysters, clams, octopus, squids
* Earthworms, leeches
Molluscs (Latin: mollis, soft)
- The second most diverse phylum of animals (after Arthropods)
- Snails, slugs, clams, octopus, squids
- Mostly marine, with some freshwater and
terrestrial species - Soft-bodies animals
- Many members excrete a hard shell made of calcium carbonate
- These shells are lost or internalized in other species
Mollusc body
- Foot: Movement and attachment
- Visceral mass: Contains most of inner organs
- Mantle: Covers the visceral mass and secretes the shell
- For many members, the mantle extends beyond the visceral mass to create the mantle cavity
- An open space which contains gills, anus, excretory organs, etc.
Bivalves
- Aquatic suspension feeders such as clams, oysters, mussels, scallops
- Two shells (bi-valves) connected by a hinge
- Strong muscle(s) close them tightly
How do Bivalves use their gills
- Gills used for feeding and gas exchange
- Water inhaled from the incurrent siphon into the mantle cavity, and pumped out from the excurrent siphon
- Gills trap food as water passes though gills
Bivalves movement
- Low mobility
- Some can swim by’ flapping’ their valves
Cephalopods
- Aquatic hunters such as an octopus and a squid
- Mantle is on the outer surface
- Shells minimized, internalized or lost
- Foot has evolved into tentacles and parts of the excurrent siphon
Cephalopods movement
- Draws water into the mantle cavity through incurrent siphon
- Contracts mantle to release water jet from the excurrent siphon, propelling the animal
- The muscular siphon can be pointed towards different positions
Ecdysozoans
- Most species-rich animal group
- Nematodes, millipedes, centipedes, crustaceans, insects, etc.
- Contains more species than all other animal, protist, fungus and plant groups combined
- I.e.,more species than all other eukaryotes combined
- Exoskeleton made of cuticle
“One who does ecdysis” meaning
Molting is part of many members development
Nematodes
- Worms, very ubiquitously found in many habitats
- Aquatic, soil, moist tissues of plants, body fluids and tissues of animals
- Many are free living, others parasitic
- Trichinella spiralis is the muscle-burrowing parasite found in pork
Caenorhabditis elegans (C. elegans)
- An adult has 959 cells or 1033 cells depending on gender
- The exact locations as well as their developmental pathways for ALL cells has been mapped
- Model organism for biology in various developmental- and medicinal fields of research
Arthropods
- Crustaceans (crabs, lobster, etc.), millipedes, insects, etc.
- Crustaceans mainly inhabit aquatic systems
- Insects dominate terrestrial environments
Arthropod body
- Segmented body with jointed-appendages
attached (making antennae, pincers, legs, etc.) - Pair of compound (multi-lens) eyes
- All body parts coated with cuticle, even the joints
Arthropods: Moulting necessary for growth
- Very expensive and dangerous for the animal
- ‘Soft shell crabs’ are crabs which have just moulted and has a soft-shell (it’s not a specific species)
Insects
- Huge diversity
- Many members co-evolved with specific plant species, especially angiosperms, as pollinators
- Mutualistic relationship
- Plants provide insects with nutrients
(nectar) to flourish on land - Insects pollinate the flowers
Insect Structure
- Segmented body: Head, Thorax and Post-Genital Region
- Three pairs of legs on the ventral side of thorax
- Usually one or two pairs of wings on the dorsal side of the thorax
- Wings are extensions of cuticles
- Can still have three pairs of legs while having wings
Incomplete metamorphosis
- Insect larva develop into adult form via metamorphosis
- Incomplete metamorphosis
- Grasshoppers, dragonflies, cockroaches,
praying mantises, lice, etc.
Gradual growth of larva into adult via
multiple moulting
* Young (nymphs) resemble adults but are immature
* Can be smaller, may have different body proportions, lacks wings, etc.
Complete metamorphosis
- Distinct, step wise growth of larva into adult via a pupal stage
- Wasps and bees, butterflies, beetles, flies, etc.
Complete Metamorphosis: Larval stages specialized
for eating
* Caterpillar,maggot,etc.
* Larval stage looks completely different from the adult
Complete Metamorphosis: Adult is specialized for
dispersal and reproduction
