Transcript MAMMALOGY AS A SCIENCE

VERTEBRATE ZOOLOGY
(VZ Lecture12 – Fall 2012 Althoff - reference PJH Chapter 10)
Amphibians: “double lifers”
PART I
Recall that….
• Only remaining ____________ tetrapods were the
SMOOTH SKIN
spring
peeper
tiger
salamander
lineages still present today:
caecilians
frogs
SIGHTLESS HEAD
salamanders
Caecilia nigncans
Evolutionary Relationship of Amphibians
to other TETRAPODS
SAUROPSIDS
SYNAPSIDA
(mammals)
AMNIOTES
TETRAPODS
(turtles, lizards, snakes,
crocodiles, & birds)
Classification of Amphibia
CLASS
SUBCLASS
Amphibia
Labryinthodonotia*
Leposondyl*
Lissamphibia
ORDER
Urodela
(salamanders)
Anura (frogs)
Gymnophiona
* = extinct
(caecilians)
Shared Derived Characters
(summarized from Table 10.1 pg221 PJH)
_________:
structure and importance to gas
exchange.
A) all have mucus glands that
keep the skin moist
B) substantial part of an amphibian’s
CO2 and O2 exchange thru skin
C) all have poison (granular) glands
in skin (some more potent than others)
_______________________: special sensory
area in wall of sacculus of the inner ear
A) area sensitive to frequencies
<1000 Hz (cycles per second)
B) Papilla basilaris (2nd area) sensitive
to frequencies >1000 Hz
Shared Derived Characters
(summarized from Table 10.1 pg221 PJH)
__________________________
COMPLEX:
most have 2 bones involved in transmitting
sound. Columella derived from hyoid arch
which is found in salamanders, caecilians,
and most frogs. Operculum associated with
fenestra ovalis of the inner ear
_____________: Salamanders and frogs have
distinctive green rods (retinal cells).
Caecilians appear to lack them but their
eyes are greatly reduced anyway (may
have had them at one time)
Shared Derived Characters
(summarized from Table 10.1 pg221 PJH)
__________________ TEETH:
Most modern
species have teeth in which crown and base
(pedicel) are composed of dentine,
separated by a narrow layer of uncalcified
dentine or fibrous connective tissue.
STRUCTURE OF THE _________________
MUSCLE: this muscle is a thin sheet in the floor
of the orbit (eye socket) that is innervated by
the 5th cranial nerve. It causes the eyes to
bulge outwardenlarging the buccal cavity.
All salamanders and anurans…modified form
in caecilians
PEDICELLATE TEETH
Anterior 
crown
outer margin of jaw
pedicel
Teeth tend to “______”
back into the mouth
where the crown and
pedicel are separated
by the fibrous tissue
Other generalities concerning amphibian ….
• All are __________________.
Mouth sizes vary
in sympatric species (comparable to what you might
recall from Darwin finches example of differentiation in
beak sizes/morphology).
• As noted, permeable skin, a shared characteristic
•
•
•
is a key feature. Even though it may seem
“primitive” (starting _____ MYA), it clearly still
“works” in some of today’s ecosystems
For other categories, much ________—
especially in the areas of a) reproduction
b) locomotion
c) defense
Ectotherms
3-chambered heart (2 atria, 1 ventricle)
Focus on SALAMANDERS
• ORDER: _________ (may see “Caudata” in older
listings/references = “bearing a tail”)
• 10 families, ~515 species
• Most species found in northern hemisphere; some
•
•
•
down to northern South America. Greatest
diversity in North America-Central America
Body form is elongate. Most have 4 functional
limbs. Moves with lateral bending & leg
movements
Largest > 1m (Japanese & Chinese giant salamanders)
In NA, largest is hellbender (<60 cm)
_______________: common trait…larva becomes
sexually mature without attaining adult body form
The mudpuppy is paedomorphic.
Also with respect to other salamander species,
it retains its external gills as a reproductive adult
Congo Eels
• 3 species in North America (lower Mississippi Valley
•
•
& coastal plains)
Have well-developed lungs….atypical for this taxon
Can survive in mud of dried ponds for up to 2
years…sort of like the LUNGFISH we’ve already
studied (recall: estivation/aestivation)
• 3-toed
• 2-toed
• 1-toed
Salamanders con’t….
• Some species are blind
•
(i.e. Texas blind
salamander)
Many are cave-dwellers
• Some are fully terrestrial (i.e., no aquatic larval
•
stage ________________ salamanders
Major family of fully terrestrial salamanders are
the Plethodontidae (common: Plethondontids)
….example of no aquatic larval stage as
young hatch from eggs as miniature adults
“fully terrestrial”
life cycle
Batrachoseps
Most salamander species have
aquatic larvae that lose their external gills
when they reach adulthood
Adult
Aquatic
larvae
(Mabee’s salamander Ambystoma mabeei)
Closer Look….Feeding Specializations
of Plethodontids
• Being lungless “frees up” the ______________
_________ to do “something else.” In “lunged”
salamanders, hyobranchial apparatus is
essential part of respiratory system
In this case, plethodontids use it to help
protrude the tongue a considerable distance
from the mouth
Feeding Specializations
of Plethodontids…con’t
• Bolitoglossine plethodontids known as the “dart
tongues” (bola is Greek for “dart”, glossa is “tongue”)
Position of eyes differs for those capable of
extended tongue protrusion. To “hit” prey, it
takes accurate projection of the tongue. Eyes
positioned ______________ (i.e., not to side of
head) and __________ more help in accuracy.
VS.
Social Behavior of Plethodontids:
SCENTING & TERRITORIALITY
• Good sense of smell.
Key feature is the
external _________________ that extends
from the external nare to around down to
the mouth on each side
• Animal obtains fluid
(moisture) on the groove
that enters external
nares nasal chamber
 over epithelial lining
of ____________ organ
Fig. 10-4 p225 PJH
Remember this for
ungulate/bison—
Flehman behavior
during rut???
Many territorial species
• Good evidence males, at least, are very
•
•
territorial. Mark territories with pheromones
Neighboring males get used to each other—
scent may elicit marking but not aggressive,
direct confrontations. But transient males
and females bring out strong responses
Experiment by Jaeger et al. 1983 with redbacked salamanders resulted in some very
interesting behavioral responses
Jaeger, R.G. et al. 1983. Foraging tactics of a terrestrial salamander: costs of
territorial defense. Animal Behaviour 31:191-193.
Observations of red-backed salamanders
in lab cages (by Jaeger and colleagues)
Male resident bites the male
intruder…less aggressively if
neighbor
Resident bites the intruder’s tail
region…intruder’s autotomizes
its tail to escape.
Consequence: takes up to year
to regrow tail and delays sexual
maturity/activity
Resident bites intruder on
snout injuring intruder’s
nasolabial groove (NLG)
1
2
3
no scar NLG with scar
Fig.10-5 pg227 PJH
Additional observations…lab and field on
red-backed salamanders
• Lab:
•
•
those with bitten snouts captured average of
5.8 fruit flies in a 2-hour period vs. 18.6 flies for
salamanders not bitten on snout
Field: sample of 144 red-backed salamanders in
Shenandoah National Forest revealed 11.8 % had
been bitten on nasolabial grooves. Those so bitten
weighed less, on average  likely do to reduced
foraging success.
Advantage of recognizing neighboring?
a)
b)
for attacks
spotted
salamander
R.G. Jaeger website
tiger
salamander
R.G. Jaeger website
slimy
salamander
R.G. Jaeger website