Homodont | Cephalopod Radula under the SEM

Vampyroteuthis infernalis – Vampire Squid

(screenshot from a Monterey Bay Aquarium Research Institute Youtube video)

Placed in its own order (Vampyromorpha; Pickford, 1936) due to the presence of sensory filaments, V. infernalis is a bathypelagic cephalopod that resides in the oxygen minimum zone at depths from 600-800m (Siebel et. al 1998). Their mass-specific metabolic rate is the lowest among all cephalopods. A historical relic as the last living species of the order Vampyromorpha, V. infernalis share characteristics of both octopods and squid (Siebel et. al 1999).

Feeding habits of V. infernais have been studied in situ observations, shipboard observations, stable isotope analysis, and gut sample analysis. These observations show a variety of prey including copepods, shrimps, squids, cnidarians, and marine snow.

V. infernalis was preserved in formalin and the buccal cavity was extracted using forceps. The radulae from this specimen measured at 4.5 mm and 3.75 mm long.

Images from V. infernalis show that this species has a homodont radula with a single cusp on all seven teeth, along with marginal plates along both sides of the rows.

Radula of V. infernalis taken by Sam Mejia

2vamp3.1.jpg
Radula of V. infernalis (with some measurements) taken by Sam Mejia

2vamp4.1.jpg
Radula of V. infernalis (with some measurements) taken by Sam Mejia

2vamp1.1.jpg
Radula of V. infernalis (with some measurements) taken by Sam Mejia

vampiresquidradula1 (1).jpg
Radula of V. infernalis taken by Sam Mejia

Radula of V. infernalis taken by Sam Mejia

V. infernalis taken by Sam Mejia

further down the radula of V. infernalis taken by Sam Mejia

V. infernalis taken by Sam Mejia

end of the radular ribbon of V. infernalis taken by Sam Mejia

Radula of V. infernalis (close up of marginal plate and marginal tooth) taken by Sam Mejia

vampiresquidradula7.2.jpg
Radula of V. infernalis taken by Sam Mejia

Rachadian tooth (middle) with lateral teeth of V. infernalis taken by Sam Mejia

vampiresquidradula9.2.jpg
Radula of V. infernalis (close up of marginal plate, marginal tooth, and lateral teeth) taken by Sam Mejia

vampiresquidradula15.2.jpg
Radula of V. infernalis (with marginal tooth torn partially off) taken by Sam Mejia

Euprymna scolopes – Hawaiian Bobtail Squid

hawaiian bobtail.JPG

Hawaiian bobtail squid

M. MCFALL-NGAI/PLOS BIOLOGY 2014

Native to the central Pacific Ocean inhabiting shallow coastal waters, E. scolopes grows to 30mm in length and feeds on a variety of food, including: mysids, brine shrimp, crustaceans, annelids, and fish. E. scolopes occur in both near-shore habitats and open ocean (to ~200m) (Lee et al. 2009).

Images from E. scolopes show that this species has a homodont radula with a single cusp on all seven teeth, with no distinctive marginal plates along both sides of the rows.

Radula of E. scolopes taken by Sam Mejia

Radula of E. scolopes taken by Sam Mejia

Radula of E. scolopes taken by Sam Mejia

Radula of E. scolopes taken by Sam Mejia

Radula of E. scolopes (with some measurements) taken by Sam Mejia

Radula of E. scolopes (with some measurements of space between teeth) taken by Sam Mejia

Sepia bandensis – Dwarf Cuttlefish

dwarf cuttlefish
-Photo by Matthew T. Ross–

S. bandensis is known to prey on mysid shrimp, crabs, amphipods, and fish. Observed in coastal shallow waters, found over coral reefs and sand (Ross 2010).

Images from S. bandensis show that this species has a homodont radula with a single cusp on all seven teeth, with no distinctive marginal plates (but possibly marginal rows) along both sides of the rows.

2bandensis1.1.jpg
Radula of S. bandensis taken by Sam Mejia

2bandensis2
Radula of S. bandensis taken by Sam Mejia

2bandensis4
Radula of S. bandensis taken by Sam Mejia

2bandensis4.2
Radula of S. bandensis (with some teeth measurements) taken by Sam Mejia

S. bandensis from Denise Whatley from Tonmo

cuttlefish1 (1).jpg
Radula of S. bandensis taken by Sam Mejia

Radula of S. bandensis taken by Sam Mejia

cuttlefish2 (1).jpg
Radula of S. bandensis taken by Sam Mejia

cuttlefish3.1.jpg
Radula of S. bandensis taken by Sam Mejia

Radula of S. bandensis taken by Sam Mejia

cuttlefish2.2 (1).jpg
Radula of S. bandensis (with some measurements) taken by Sam Mejia

cuttlefish1.2.jpg
Radula of S. bandensis (with some measurements) taken by Sam Mejia

Sepia officinalis – Common cuttlefish

sepia officinalis Image result for sepia officinalis

In an experiment where 522 specimen were caught off the coast of Algarve, Portugal, S. officinalis had the prey of 49 different species belonging to six taxa (Bivalvia, Cephalopoda, Crustacea, Gastropoda, Polychaeta and Teleostei). For smaller specimen, crustaceans are a big appeal due to weight, where larger specimen had more fish contents in their stomach. Seasonal differences in diet were apparent and may influenced size of the cuttlefish (Alves 2006).

Images from S. officinalis show that this species has a homodont radula with a single cusp on all seven teeth, with some kind of marginal plate or marginal along both sides of the rows.

officinalis2
Radula of S. officinalis taken by Sam Mejia

officinalis5
Radula of S. officinalis taken by Sam Mejia

officinalis6
Radula of S. officinalis taken by Sam Mejia

officinalis3
Radula of S. officinalis taken by Sam Mejia

officinalis4.1
Radula of S. officinalis (with some measurements) taken by Sam Mejia

Nautilus pompilius – Chambered Nautilus

chambered nautilus Image result for nautilus pompilius

Images from N. pompilius show that this species has a homodont radula with a single cusp on all teeth, with two rows of marginal plates along both sides of the rows. There are a total of 13 elements present.

Figure. Radula of Nautilus pompilius. Drawing modified from Naef (1923).

Radula of N. pompilius taken by Sam Mejia

nautilus1 (1)
Radula of N. pompilius taken by Sam Mejia

nautilus2 (1)
Radula of N. pompilius taken by Sam Mejia

Radula of N. pompilius taken by Sam Mejia
(close up of the rachadian tooth with smaller lateral teeth besides it)

nautilus7
Radula of N. pompilius taken by Sam Mejia
(close up of marginal teeth and marginal plates)

nautilus2.2
Radula of N. pompilius (with some measurements) taken by Sam Mejia

Sepioloidea lineolata – Striped pyjama squid

striped pyjama squid Image result for sepioloidea lineolata

Images from S. lineolata show that this species has a homodont radula with a single cusp on all seven teeth, with some kind of marginal plate or marginal along both sides of the rows.

lineolata1.3
Radula of S. lineolata taken by Sam Mejia

Radula of S. lineolata taken by Sam Mejia

lineolata3.2
Radula of S. lineolata (with some measurements) taken by Sam Mejia

Metasepia pfefferi – Flamboyant Cuttlefish

metasepia pfefferi Image result for metasepia pfefferi

Images from M. pfefferi show that this species has a relatively homodont radula with a single cusp on 5 teeth and possibly 2 cusps on both marginal teeth, with possible marginal plates along both sides of the rows.

pfefferi2.1
Radula of M. pfefferi taken by Sam Mejia

Radula of M. pfefferi taken by Sam Mejia

pfefferi6
Radula of M. pfefferi taken by Sam Mejia

Radula of M. pfefferi (with some measurements) taken by Sam Mejia

pfefferi2.2 (1)
Radula of M. pfefferi (with some measurements) taken by Sam Mejia

pfefferi5.2
Radula of M. pfefferi (with some measurements) taken by Sam Mejia

References

Naef, A. (1921/23). Cephalopoda. Fauna und Flora des Golfes von Neapel. Monograph, no. 35. English translation: A. Mercado (1972). Israel Program for Scientific Translations Ltd., Jerusalem, Israel. 863pp., IPST Cat. No. 5110/1,2.

Tree of Life Cephalopod Radula Authored by Richard E. Young, Michael Vecchione, and Katharina M. Mangold (1922-2003)