Invertebrate Lineages

Question 1

Porifera

Answer 1

• phylum of invertebrates called sponges that do not have tissues, though they do have specialized cells
• lack symmetry
• larval stages are mobile, but adults are sessile (non-motile)

Question 2

Cnidarians

Answer 2

• phylum that includes sea anemones, corals, and jellyfish
• radically symmetric
• diploblasts with true tissues
• incomplete digestive tract
• some species are motile, some are non-motile
• lack a respiratory system, so their bodies are very thin to allow gas exchange

Question 3

Acoelomorpha

Answer 3

subphylum of animals called flatworms but they are distinct from true flatworms (Platyrelminthes)
- bilaterally symmetric
- lack a gut and coelom
- lack other organ systems
- since they lack a respiratory system they must be flat to exchange gas
- may be descendants of the earliest lineages of animals that diverged from diploblasts, but lack the features of typical triploblasts

Question 4

Protostome

Answer 4

• triploblastic animals
• the mouth is the first part of the digestive tract to develop during embryogenesis
• bilaterally symmetric
• cephalization
• most have a coelom, CDT, and complex organ system
• 2 SUPERPHYLA: Lophotrochozoans + Ecdysozoa

Question 5

Superphylum Lophotrochozoans

Answer 5

compose a superphylum of a diverse group of PROTOSOMES that include primarily soft-bodied invertebrates and have 2 different phyla of ‘worms’
(Platyhelminthes, Annelida, Mollusca, Bryozoa, Ronfera)

Question 6

Platyhelminthes

Answer 6

phylum of “true” flatworms
- triploblasts
- lack a coelom
- have an incomplete digestive tract
- flat bodied

Question 7

Annelida

Answer 7

phylum of segmented worms that include earthworms + more
- nervous system
- CDT
- circulatory system
- skin as respiratory system
- muscles move a hydrostatic skeleton formed by a coelom

Question 8

Mollusca

Answer 8

2nd largest phylum of invertebrates after Arthropoda
- predominately marine soft-bodied animals like snails, slugs, clams, mussels, squids, octopuses, etc.
- morphologically diverse but are all unsegmented
- have nervous system
- 2 pairs of main nerve cords

Question 9

Superphylum Ecdysozoa

Answer 9

PROTOSOMES named for the process of ecdysis - the shedding/molting of the exoskeleton
- these animals have a hard cuticle that covers their bodies which must be periodically shed and replaced for them to increase in size
- the cuticle provides a tough and flexible exoskeleton that protects these animals from water loss + external environment
- NEMATODA + ARTHROPODA

Question 10

Nematoda

Answer 10

phylum of animals called roundworms due to a cylindrical morphology
- triploblastic
- bilaterally symmetric
- pseudocoelom
- covered in an external cuticle that provides structural support, protection, and muscle attachment point for movement
- CDS
- nervous sytem
- hydrostatic skeleton
- cuticle-based exoskeleton
- LACK a respiratory and circulatory system

Question 11

Arthropoda

Answer 11

LARGEST PHLYUM IN ANIMALIA (~85% of known living species)
- have hard exoskeletons made of chitin
- jointed appendages
- triploblastic
- bilaterally symmetric
- true coelom
- segmentation
- CDS, nervous, and excretory system
- 5 subphylua: trilobitomorpha (extinct), hexapoda (insects), myriapoda (millipedes + centipedes), crustaceans, chelicerata (scorpions)

Question 12

Deuterostomes

Answer 12

triploblastic animals where the anus is the first part of the digestive tract to develop during embryogenesis; 2 phyla:
1. Echinodermata
2. Chordata

Question 13

Echinodermata

Answer 13

deuterostome phylum names for their spiny skin
- EX: sea stars, urchins, sea cucumbers, sand dollars
- bilaterally symmetric larvae and pentaradial symmetric adults
- nerve ring and 5 radial nerves that extend along the arms
- CDS + circulatory system without a heart
- WATER VASCULAR SYSTEM that functions in a gas, nutrients, and water exchange and helps with movement

Question 14

Chordata

Answer 14

Deuterostome phylum consisting of animals with a NOTOCHORD
- INVERTEBRATES AND VERTEBRATES
- invertebrate chordates include tunicates and lancelets
- all chordates have a notochord, hollow dorsal nerve chord, pharyngeal slits, and muscular post-anal tail

Question 15

Invertebrate Evolution through Geologic Time

Answer 15

• animal evolution begins during the Proterozoic Eon, with fossils indicating that multicellular animals were present prior Cambrian Explosion
• Kimberlla may have been an early bilaterian (includes all triploblastic)
• animals greatly diverse after the Explosion which initiated the Phanerozoic
• fossils in the Cambrian includes early echinoderms, arthropods, and molluscles, which were likely marine and moved onto land late Cambrian

Question 16

Insects

Answer 16

first appear in the FR mid-Paleozoic Era
- records indicate that the Carboniferous period featured the largest insects + arthropods seen on Earth
- their size could be because of the higher atmospheric oxygen levels that could support bigger metabolisms

Question 17

Insects + Angiosperm Coevolution

Answer 17

with the evolution of angiosperms during the Mesozoic Era, insects and flowering plants developed mutualistic relationships based on pollination
- insects who were pollinators experienced an ADAPTIVE RADIATION as flowering plants became dominant