LecturePhylum Mollusca (Scaphopoda and Aplacophora)Phylum Annelida

Mollusca: Scaphopoda and Aplacophora
Top: Scaphopodan shell and foot
Bottom: Chaetodermomorph (photo) and neomeniomorph (photo) aplacophorans

Today we briefly covered the lesser known molluscan groups Scaphopoda ("boat-like foot" molluscs) and Aplacophora (molluscs "without a shell"). We discussed their bauplan and some of their most important aspects of their ecology.

Annelida
Left column: An errant and a sedentary polychaetes
Right column: Clitellates - Oligochaeta (photo) and Hirudinea (photo)

Then we began discussing the phylum Annelida, the segmented worms. We began with their bauplan, and then started with one of the groups: Polychaeta, the most diverse of the annelids. We covered their general characteristics and focused on the errant polychaetes.  Next week, the sedentary polychaetes, and the clitellates.
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Lecture - Phylum MolluscaCephalopoda

Today we discussed some of the key features of each one of the extant groups of cephalopods.  Then we proceeded to discuss some of the most important features of cephalopods as a whole and their variation across different groups.  We discussed:

• Shell evolution - Presence/absence, location, material, function
• Feeding - Beak and radula
• Locomotion - Crawling and swimming. Using fins and using siphons for jetting
• Nervous system and complex behavior
• Reproduction and development

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Lecture - Phylum MolluscaBivalvia (Lamellibranchs)Cephalopoda

FRIDAY, APRIL 20, 2012

Some lamellibranch bivalves (all unionids) from the Mussels of Illlinois website

(entry in progress)
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Field trip - Hog Creek in Hardin Co.

THURSDAY, APRIL 19, 2012

Information and pictures from the field trip coming soon

Location of the sampling site, about 7miles east of ONU

Google Maps image of the sampling site 
Hog Creek (Allen Co., OH),  on Ada Rd/HWY 81, 0.5 mi (0.8 Km) west of the junction with N Phillips Rd.

(entry in progress)
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Lecture - Phylum MolluscaGastropoda (Opistobranchs and Pulmonates)Bivalvia (Protobranchia)

Today we finished our discussion on gastropods, by describing the diversity and defining anatomical characters of the opistobranchs (mainly the presence of rhinophores, cerata or gill plumes, complete detorsion, and reduction or loss of shell, ctenidia, and mantle cavity).

We then turned our attention to pulmonates, gastropods that have colonized terrestrial and freshwater environments, mainly through the loss of ctenidia and gills, and the development  of a highly vascularized mantle cavity which acts as if it were a lung (hence the name 'pulmonates').  Some have also lost the shell.

We started the discussion of the class Bivalvia, the group comprising oysters, scallops, clams, and mussels. We discussed their general body plan and did overview of their life cycle, including a special mention of the modified veliger state of Unionoidea: The parasitic glochidium larva.

We mentioned that we will divide the Bivalvia into the traditional groupings of Protobranchia and Lamellibranchia (with no current taxonomic validity), and explained how the lamellibranchs can use their gills to filter food.


(entry in  progress)
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Exam 2

Today we had our second exam. Stats:

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Wild and Bizarre Inverts Seminar

The Wild and Bizarre Inverts project is an exercise that highlights adaptations that some invertebrates have that defy our conventional view on animal biology.
Many animals have morphological or behavioral adaptations that are very different from what most people are used to see in animals (vertebrates or invertebrates).  For such reason they tend to awe those who do not study the lesser known phyla or lesser known species in well known phyla.

Students in this course picked an example that appealed to them and prepared a paper and a presentation highlighting unusual anatomical, physiological, or behavioral adaptations in invertebrates.

Wild and bizarre cnidarian and lophotrochozoans
Clockwise from top: Siphonophore (Marrus orthocanna), Christmas Tree worm (Spirobranchus giganteus),
Mimic octopus (Thaumoctopus mimicus), and Vampire squid (Vampiroteuthis infernalis)

Wild and bizarre ecdysozoans (all panarthropods)
Left to right from top: Water Bear (Tardigrada), Velvet worm (Onychophora),
a Pistol Shrimp (Alpheus sp.), Goliath Bird-Eater tarantula (Theraposa blondi),
Japanese Spider crab (Macrocheira kaempferi), and the Orchid mantis (Hymenopus coronatus)

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Lecture - Phylum MolluscaGastropoda

(entry in progress)
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Lecture - Phylum molluscaMonoplacophora and Polyplacophora

Mollusc larvae
A chiton's trochophore, a snail's veliger, and a freshwater clam's glochidium

Today we continued reviewing some of the general characteristics of molluscs and started the discussion of the main classes.

We talked about the general mode of reproduction in molluscs and discussed the larval stages that characterize the phylum: trochophora, veliger, and, in some cases (Unioniodea), glochidium.
We even mentioned one of the masterpieces of scientific poetry: The Ballad of the Veliger, by Walter Garstang (worth the read, for mollusc larval development and for understanding torsion in gastropods)

We then discussed the result of adaptive radiation in molluscs, which gave rise to the diversity we observe today, from an ancestral mollusc. We talked a little about mollusc phylogeny too.

After discussing such intraphylum diversity we started talking about the first classes: Monoplacophora and Polyplacophora (chitons).  For both groups we discussed how their characteristics differ from those covered when discussing the generalized mollusc.  We payed special attention to the shell, the foot, the mantle cavity and the visceral mass.

Monoplacophorans and a polyplacophoran

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