Thursday, March 22, 2012

Blog Entry 6: Serpentes/Ophidia: Brad and Michele

Serpentes/Ophidia: Brad and Michele

Location: John Carroll University Ecology Lab
Time: March 1 & 16th 2012, 1:30pm
Objective: Identify and recognize the diversity of Serpentes (Ophidia)

Serpentes is a highly diverse clade that is broken up into 16-23 families (based on whom you reference). Some of the main families that we focused on include representatives from: Pythonidae, Boidae, Colubridae, Elapidae, and Viperidae. Some of the synapomorphies that define these groups overall include: fused premaxillae, fused parietals, reduced nasals, lack of vomerine teeth, specialized joints between ulna-ulnare and radius-radiale, specialized ankle joints, well developed hemipenes, saccular ovaries, Jacobson’s organ (vomeronasal organ) separated from nasal capsule, lacrimal duct joining the vomeronasal duct, femoral and pre-anal glands, and egg tooth at hatching.

While much of the lab was focused on the diversity, we began with learning some of the basic anatomy, articulation and kinesis of the skull.

Snakes are significantly different from lizards for many reasons, with one of the main reasons being the presence of extreme cranial kinesis and streptostyly (where the quadrate can dislocate from the lower jaw to facilitate the wide opening of the mouth). There are approximately six points of articulation in a typical snake skull:

1. Lower jaw and Quadrate
2. Quadrate and Supratemporal
3. Supratemporal and Parietal
4. Dentary and Compound bone
5. Prefrontal and Maxilla
6. Frontal and Nasal

Below are pictures of skulls with the bones labled and points of articulation labeled on the Proteroglyphous skull.

Another point of anatomy that we focused on was the dentition, with specific focus on the teeth and fang arrangements. Overall, there are four major teeth and fang categories:

1. Aglyphous – These types of teeth do not have grooves and are conical, “typical” teeth found in all species of snakes.

Lampropeltis getula californiae putting those Aglyphous teeth to work!

2. Opisthoglyphous – rear-fanged teeth with a groove, aiding in venom injection - Found in Colubridae

Heterodon nasicus (Hognose snake) skull

3. Proteroglyphous – hollow, front-fanged teeth with relatively static movement on a small maxilla - Generally found in Elapidae

Cobra skull with points of articulation circled.

4. Solenoglyphous – hollow, retractable/protractable fangs positioned on a kinetic maxilla. These are the most derived teeth which allow for deep injection - Generally found in Viperidae

Rattlesnake skull

The second main portion of the lab focused on observing some specific key families among the Serpentes in both Henophidia (“old” snakes) and Caenophidia (“new” snakes).

Boidae:Distribution: W. North America – Subtropical S. America, West Indies, Central Africa, S. Asia, Madagascar, S.W. Pacific islands
Characteristics: Cranial infrared receptors in interlabial pits, hindlimb vestiges-cloacal spurs, pelvic remnants, non-venemous, aglyphous
Genera: 7
Distribution: Tropical Americas, W. Indies, Madagascar, S.W. Pacific
Characteristics: Labial sensory pits occur, mostly arboreal

Genera: 4
Distribution: W. North America, Central Africa, Asia, W. China
Characteristics: Labial sensory pits absent, semi-fossorial.

Pythonidae: Pythons
Genera: 8
Distribution: Sub-Saharan Africa, S. and S.E. Asia-Australia
Characteristics: non-venemous, vestigial spurs, constrictors, labial pits set in scales, aglyphous

Colubridae: Colubrids
Distribution: Worldwide
Characteristics: Most structurally diverse group (show all fang types), NO cranial infrared receptors occur in pits or surface indentations, girdle elements absent externally and internally.
Genera: more than 100
Distribution: Worldwide
Characteristics: Highly diverse biology and ecology (family characteristics)

Lampropeltis triangulum

Genera: more than 90
Distribution: Americas
Characteristics: Terrestrial, primarily oviparous, venomous (but not usually harmful to humans), Opisthoglyphous

Lower snake: Carphophis amoenus

Genera: 38
Distribution: N. America, Africa, Eurasia, E. Indies.
Characteristics: Mainly aquatic species, fish and amphibian specialists

Elapidae: Cobras, Kraits, Sea Snakes, Death Adders and Allies
Genera: more than 100
Distribution: S. North America – S. South America, Africa, S. Asia, India, Pacific oceansCharacteristics: venomous, no cranial infrared receptors, proteroglyphous

Genera: 43
Distribution: S. North America – S. South America, Africa, S. Asia, India, Pacific oceans
Characteristics: Laterally compressed, paddle tail, loss of enlarged ventral scales (photo below), viviparous , terrestrial and aquatic taxa.

Genera: 17
Distribution: Americas, Africa, Eurasia, E. Indies, Phillipines
Characteristics: Ophiophagus (eat snakes), fossoreal species are aposematic, arboreal, aquatic, but mostly terrestrial, and mostly oviparous.

Viperidae: Vipers and Pit Vipers
Distribution: Worldwide, except Papuaustralia and oceanic islands.
Characteristics: venomous, solenoglyphous
Genera: 1
Distribution: South and Central China, Burma, and Vietnam
Characteristics: Lack a loreal pit, semi-fossoreal, may dehydrate rapidly in dry environments
Genera: 26
Distribution: S.W. and S. Asia and the Americas
Characteristics: Well developed loreal pit for infrared receptors, most viviparous, some oviparous (more basal), rattles present except in basal species.

Genera: 13
Distribution: Africa, Europe, and Asia
Characteristics: Lack loreal pits, oviparous and viviparous taxa, don’t exceed greater than 2m, terrestrial

Ohio species to know:


  • Nerodia sipedon sipedon (Northern Water Snake)
  • N. s. pleuralis (Midland Water Snake)
  • N. erythrogaster neglecta (Copperbelly Water Snake)
  • Regina septemvittata (Queen Snake)
  • Thamnophis butleri (Butler’s Garter Snake)
  • Thamnophis sirtalis sirtalis (Eastern Garter Snake)
  • T. radix radix (Eastern Plains Garter Snake)
  • T. sauritus sauritus (Eastern Ribbon Snake)
  • T. sauritus septentrionalis (Northern Ribbon Snake)
  • Storeria dekayi wrightorum (Midland Brown Snake)
  • S. dekayi dekayi (Northern Brown Snake)
  • S. occipitomaculata occipitomaculata (Northern Redbelly Snake)
  • Virginia valeriae valeriae (Eastern Smooth Earth Snake)
  • Diadophis punctatus edwardsi (Northern Ringneck Snake)
  • Heterodon platyrhinos (Eastern Hognose Snake)
  • Carphophis amoenus amoenus (Eastern Worm Snake)
  • C. a. helenae (Midwest Worm Snake)
  • Opheodrys vernalis (Smooth Green Snake): much of state
  • O. aestivus (Rough Green Snake): southern third of state
  • Coluber constrictor foxii (Blue Racer)
  • C. c. constrictor (Northern Black Racer)
  • Pantherophis obsoletus obsoletus (Black Rat Snake)
  • P. vulpina (Fox Snake)
  • Lampropeltis triangulum triangulum (Eastern Milk Snake)
  • L. getula nigra (Black Kingsnake): southern part of state
  • Agkistrodon contortrix mokasan (Northern Copperhead: Mokasan)
  • Sistrurus catenatus catenatus (Eastern Massassauga)
  • Crotalus horridus (Timber Rattlesnake)

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