BY 124 SI Worksheet 12 Answers
A land snail, a clam, and an octopus all share
a. Embryonic torsion
b. Distinct cephalization
c. A mantle
d. Gills
e. A radula
Which of the following animals is most closely related to spiders?
a. Centipedes
b. Scorpions
 What phyla and subphyla do they share? Arthropoda, Chelicerata
c. Pill bugs
d. Mosquitos
e. Grasshoppers
Sowbugs are really crustaceans, not insects. Therefore, a sowbug does NOT have
_____.
a. An open circulatory system
b. Jointed appendages
c. Three pairs of legs
 How many legs must it have? 7 pairs – not important just know that
crustaceans have highly modified appendages!
d. Antennae
e. An exoskeleton
In most insects, gas exchange is accomplished by _____.
a. Flame bulbs
 What phylum are flame bulbs first seen? Platyhelminthes.
b. Lungs
c. Book lungs
 What subphyla are these located? Arachnida – function in respiration
d. A tracheal system
 What subphyla? Hexapoda
e. Diffusion across the exoskeleton
 Possibly some Nematodes
A _____ is a chordate but not a vertebrate.
a. Lancelet
b. Sea star
c. Shark
d. Lamprey
e. Frog
Which of the following chordate characteristics contributes most to the formation of
your ears?
a. Notochord
b. Dorsal, hollow nerve cord
c. Pharyngeal slits or clefts
d. Muscular, post anal tail
e. None of the above
A lamprey, a shark, a lizard, and a rabbit share all the following characteristics
except _____.
a. Pharyngeal clefts in the embryo
b. Hinged jaws
 Which one does not have a hinged jaw? Lamprey
c. A dorsal, hollow nerve cord
d. Vertebrae
e. All of the above
What is the difference between the notochord and the dorsal, hollow nerve
Figure 34.3
cord? What does each of them develop into in humans?
1. Notochord – a longitudinal, flexible rod
Dorsal,
located between the digestive tube and the
hollow
Muscle
nerve cord.
nerve cord
segments
- Composed of large fluid-filled cells
Notochord
encased in fairly stiff, fibrous tissue.
It provides skeletal support and can
provide a structure for muscles to
work against.
- Usually a more complex skeleton
develops around the ancestral
Anus
Pharyngeal
notochord. In humans it is the disks
Muscular,
slits
or clefts
sandwiched between vertebrae.
post-anal tail
2. Dorsal, hollow nerve cord – develops
from a plate of ectoderm that rolls into a tube located dorsal (on top) of the notochord.
Unique to chordates.
Some phyla have solid nerve cords. The cord develops into the nervous system, brain and spinal
cord
What type of circulatory system is present in the following?
Earthworm – Closed
Lobster – open
Shark – closed
Human – closed
Mouth
Cricket – open
In what type of animal would you find a book lung? What is its purpose?
Inside a chelicerate. (sea spider, horseshoe crab, scorpion, tick, mite, spider) Book
lungs are for gas exchange. stacked, plate like structures containted in an internal
chamber. Large surface area helps with CO2 exchange.
What are two ways that centipedes and millipedes differ?
Millipedes – two sets of legs per segment and herbivores
Centipedes – one set of legs per segment and carnivores
Compare and contrast incomplete and complete metamorphosis.
Incomplete – young resemble adults but are smaller, have different body
proportions and lack wings. (grasshoppers) After a series of molts the youth
resembles the adult
Complete – have larval stages for feeding and growing (caterpillar, maggot, grub)
that looks entirely different from adult stage, which is for dispersal and
reproduction.
True or false? Tunicates retain most chordate characteristics throughout their lives.
False. After metamorphosis many chordate characteristics disappear. Adults draw
water through an incurrent siphon and out an excurrent siphon. Some can use the
siphon to shoot a jet of water, “sea squirts”
Describe the purpose of the “neural crest” in craniates
The Neural crest is a collection of cells that appears near the dorsal margins of the closing neural
tube in an embryo. These cells disperse throughout the body, where they give rise to structures
like teeth, some bones, cartilage of the skull, the dermis of the facial region, types of neurons, and
sensory organs.
What order of insect:
Has two pairs of wings, large hind legs, courtship sounds by rubbing legs together?
Orthoptera (grasshoppers)
Feeds with a long proboscis on nectar?
Lepidoptera (butterflies moths)
Has one pair of wings, mouthparts for sucking, well developed compound eyes?
Diptera (housefly)
What species of echinoderm:
Has no arms but rows of tube feet for locomotion and protection. A highly complex
rigid mouth for seaweed. Very little evolution throughout history?
Echinoidea (sea urchins, sand dollars)
Arms radiating from central disc with tube feet. Gripping from adhesive chemicals
and not suction. Eat their prey by opening up their stomach and engulfing.
Considerable regenerative abilities?
Asteroidea (common starfish)