Feeding and Digestion of Carcharocles Megalodon

Introduction:

The Carcharocles Megalodon, commonly known as “The Big Toothed Shark”, was also

known for its food requirements of 2000 pounds of food a day (DeSantis, 2007). The constant

moving and jonesing for food causes this animal to have a high daily metabolic rate of 47941.2

kJ/day. This megalodon sustained itself with other tertiary consumers such as Pinnipeds (seals),

odontocetes (dolphins), and mysticetes (baleen whales) along southeastern and gulf coasts, and

smaller sharks (Klimley, 2013, pg. 38). Although there aren’t evidence found that smaller sharks

were a part of this species diet, it could be assumed that it could have since its closest living

relative, the great white shark”, currently eats smaller shark species. There hasn’t been evidence

of this species having symbionts either, but a symbiotic relationship would have existed with a

species similar to remora or sharksuckers, the symbionts of the great white shark (Norman,

Reynods et.al, 2021).

Its diet of mainly tertiary consumers resulted in the most powerful bite force out of all the

marine predators (Cooper, Pimiento et. al, 2020). It had a large mouth diameter that spanned

nearly 3 meters wide and contained rows of serrated teeth that grew up to 10 cm long (Kimley,

2013, pg. 38). This species has a holostylic jaw which allows for its teeth to be a saw to cut up its

prey, thus immobilizing its prey (Klimley, 2013, pg. 318, 322). The feeding behavior that this

shark used was to stalk its prey by blending in with its surroundings and attacking its prey

immediately after (Klimley, 2013, pg. 316).

Figure 1. Minh Tran’s original drawing of Holostylic Jaw Suspension seen in CarcharoclesMegalodon with distinctive structures labeled (Klimley, 2013, pg. 322)

Not only does this predator have the advantage from its jaw suspension, but it also has

different phases in its feeding phases to make sure that its prey is being properly immobilized

and digested. The feeding phase consists of four parts: the preparatory phase, expansive phase,

compressive phase, and the recovery phase (Klimley, 2013, pg. 320). The preparatory phase

allows for the mouth to be slightly opened for water to flow through the gills (2013, pg. 320).

The expansive phase is when the lower jaw is lowered up and the head goes up to catch its prey

(2013, pg. 320). The compressive phase is when its mouth opens wide followed by the recovery

phase, when the jaw is retracted and goes back to its normal state (2013, pg. 320).

Figure 2. Minh Tran’s original drawing of bio-mechanics of different feeding phases inCarcharocles Megalodon. Diagram consists of visuals of preparatory, expansive, and recoveryphases. Labeled structures in each phase relate to the muscles present during each specific phase,red lines represent the muscles used to execute jaw movement in each phase, green arrowsrepresent the direction of the jaw movement in each phase, and the yellow arrows represent thedirection of the muscle contraction in each phase (Klimley, 2013, pg. 325)

Figure 3. Minh Tran’s original drawing of the internal anatomy of Carcharocles Megalodon fromesophagus to anal opening. Close-up of intestines also included to reveal spiral intestines.(Klimley, 2013, pg. 353-354)

These feeding phases are then followed by gastric digestion. Gastric digestion is a type of

anaerobic digestion that breaks down its prey with gastric juices in the stomach. Digestion is

carried out with the mucus producing tissues in the intestine such as hydrochloric acid, protease

enzymes like pepsin, and other breakdown enzymes that aid in its digestion (Papastamatiou,

Lowe, 2005). Contrary to its size, similar to its closest living ancestor, the great white shark, this

predator most likely had spiral intestines, which allowed for a compact intestine, allowing for

space for the peritoneum, liver and uterus (Klimley, 2013, pg. 353-354). The intestine length of a

shark is oddly enough, shorter compared to other marine mammals (Klimley, 2013, pg. 352-353).

Although the mucosa tissue increases, the intestine of the surface area, digestion is sustained due

to compact spacing (2013, pg. 352-353). The compact nature of spiral intestines allow for the

peritoneum, liver, and uterus to take up more space, causing a delay in digestion, supporting why

this species can go for a long time without eating, supporting its diet in respect to how big it is.

Methods:

Calculations of the macronutrients were based on three animals, the blue whale, mako

shark and sea lion. The nutrient contents were found from USDA agricultural research service

and made into a percentage of the total body content. Protein, carbohydrate and lipid daily intake

requirements were derived from 15.9 kJ/g, 39.2 kJ/g, and 20.1 kJ/g respectively (Withers, 1992).

These values were then used to calculate a daily budget of food intake according to the DMR of

the megalodon at 1150588.8 kJ/day (Minh, 2021). From the macronutrients the total absorption

was found to be 80% of the total intake (Withers, 1992). Values from these nutrients were then

based off of the total absorption. Total animal consumption per day was then established

according the the average weight of each animal.

Grams of glucose per day obtained through diet was achieved by using the blood glucose

levels in sharpnose sharks. Futhering the glucose obtained through diet was achieved by using

blood lactate levels through gluconeogenesis (Hoffmayer, Parsons, 2003).

Given that the animals eaten contained high levels of protein, this was set as the limiting

factor. The equation used to caculate surface area was Q10 = (R2/R1)^10/(T2-T1) and the

protein constant was 86 nmole/min/cm^2 at 20 C for general fish (Withers). With the surface

area we were then able to find the intestinal length and volume using the following equations

SA = pi(d)(l) and V = (pi)(l) cm ^2, respectively. Since the inner and outer diameters of the

megalodon is unknown a the intestine parameters was used from a shark species and then scaled

to the size of the megalodon.

Results:Table 1. Average macronutrient intake needed to support DMR of megalodon according toanimal consumption.

Protein(g/day)

Carboh-ydrates(g/day)

Lipids(g/day)

Grams needfor DMR ofmegalodon(g/day)

Percentage of animalconsumed daily according toDMR (%)

Bluewhale

30560.6 0 21019.6 124009.4 0.1

Makoshark

52075.9 0 9987.5 243004.8 82.3

Sealion

49536.3 0 11289.7 192001.3 100.06

Table 2. Dimensions of estimated intestine and glucose consumption for brain metabolism.

IntestinalSurface Area(cm^2)

Intestinallength(m)

Intestinalvolume(liters)

Glucose forbrainmetabolism(g/day)

Carcharocles

megalodon

1420163.1 196 61566.9 17.2

Table 3. Glucose intake of Carcharocles Megalodon from diet found through compared toglucose production through gluconeogenesis

Diet (Blood Glucose) Gluconeogenesis (Blood Lactate)

56.5920g/day 124.85 g/day

Discussion:

From the results, the intestine of this animal has an unexpectedly small diameter of

23.067 cm compared to its size. Considering that it’s the largest shark to ever exist, a small

diameter was expected. Although, a smaller diameter does make sense due to the compactness of

the intestines. Since the intestines don’t have a lot of space in the internal anatomy due to the

peritoneum, liver, and uterus taking up most of the space, the diameter would have to be smaller

for the spiral intestines to conform.

Although the compact intestines allow for a longer length of absorption, it would cause a

slower digestion since the food stays in the stomach longer to break down its food with

breakdown enzymes of high acidity. This would support the fact that for its size, it has a smaller

metabolic rate. Considering that this animal has a daily metabolic rate of 1150588.8 kJ/day and a

mass of 45000 kg, this would mean that more energy would need to be put into breakdown

food,which supports their requirement to not feed as much. Since they unexpectedly don’t feed

as often due to the slower digestion rate, they would need a high fiber diet, explaining why its

diet has high protein content.

As for its glucose intake, its diet doesn’t directly contain glucose, it would support why

blood glucose is so low. The diet itself contains only 59.5921g/day of glucose, which isn’t

enough to support its digestion considering that the brain alone needs 17.2g/day, but a massive

daily metabolic rate. To support its large metabolism, the animal attains glucose from

gluconeogenesis releasing lactic acid to be converted into glucose. The glucose that

gluconeogenesis produces came out to be 124.85 g/day, added with the 59.5921g/day seems to

support its digestion. Although this animal doesn’t get enough glucose from its diet, it produces

its own glucose through gluconeogenesis.

For the surface area of the intestines it proved to be extreamly large and given that the

intestinal length is relatively short this would make sense because they would be able to absorb

more nutrients in a shorter amount of space.

● Talk to Dr. Butler about intestine calculation, intestinal length, volume and

surface area is way to large.

● We observed that intestinal length and volume was very short and compact

compared to its size.

● This makes sense because other internal organs like the liver alone take up to

25% of the body mass (Pethybridge, 2014). This organ helps the shark maintain

buoyancy because of the absence of a swim bladder. Which intern lowers the

metabolic rate which plays a significant role in food intake.

● Short intestinal size meant that food needed to be absorbed very fast. This was

done with spiral valves and allowed for complete digestion of food. The more

food that was absorbed the less the megalodon had to eat.

● The megalodon was able to go long periods of time without food given that a high

absorption rate meant that they were able to benefit from majority for there food

intake.

Respective Contribution: Minh Tran (Co-Author) wrote the introduction, rechecked Ashton’s

calculations, and did the methods, results, and appendix for the direct glucose intake from diet

and gluconeogenesis . Ashton Enos (Lead Author) wrote the methods, results and appendix for

other calculations. Discussion was written by both authors. Work cited and in-text citations were

done individually.

Work Cited:

Alahyene, J., & Chiahou, B. (2020, December 6). The Growth Parameters of the Mako SharkIsurus Oxyrinchus (Rafinesque, 1810) in the Moroccan Central Atlantic Coast. Retrievedfromhttps://ejabf.journals.ekb.eg/article_172860_b9f5779867c47d1a0c97854609f61f9b.pdf

Collareta, A., Lambert, O., Landini, W., Celma, C. D., Malinverno, E., Varas-Malca, R., . . .Bianucci, G. (2017, January 04). Did the giant extinct shark Carcharocles megalodontarget small prey? Bite marks on marine mammal remains from the late Miocene of Peru.Retrieved from https://www.sciencedirect.com/science/article/pii/S0031018216305417

Cooper, J. A., Pimiento, C., Ferrón, H. G., & Benton, M. J. (2020). Body dimensions of the

extinct giant shark Otodus megalodon: a 2D reconstruction. Scientific Reports, 10(1),

N.PAG. https://doi-org.eres.library.manoa.hawaii.edu/10.1038/s41598-020-71387-y

Happyalita, U. C., & Kamila, N. L. (2019). Anatomical Structure of Shark Fish Digestive(Carcharhinus sorrah). Proceeding International Conference on Science and Engineering,2, 169-171. https://doi.org/10.14421/icse.v2.78

Hoffmayer, E., & Parsons, G.R. (2003). The physiological response to capture and handlingstress in the Atlantic sharpnose shark, Rhizoprionodon terraenovae. Fish Physiology andBiochemistry. http://sedarweb.org/docs/wsupp/S21_RD15_Hoffmayer&Parsons%202001.pdf

Klimley, A. P. (2013). The biology of sharks and rays. The University of Chicago Press.

Lockyer, C. (1991). Body composition of the sperm whale, Physeter catodon, with specialreference to the possible functions of fat depots. Retrieved fromhttps://www.researchgate.net/publication/262606020_Body_composition_of_the_sperm_whale_Physeter_catodon_with_special_reference_to_the_possible_functions_of_fat_depots.

Minh, Tran. Enos, Ashton (2021, September). The Effects of Metabolism and Heat inHomeostasis of Carcharocles Megalodon

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION | U.S. DEPARTMENT OFCOMMERCE, (2020) . Retrieved from https://www.fisheries.noaa.gov/

Nishiwaki, M. (1950). On the Body Weight of Whales. Retrieved fromhttps://www.icrwhale.org/pdf/SC004184-209.pdf.

NOAA Fisheries. (n.d.). Blue Whale. Retrieved fromhttps://www.fisheries.noaa.gov/species/blue-whale

Norman, B. M., Reynolds, S. D., & Morgan, D. L. (2021). Pacific Conservation Biology.Three-way symbiotic relationships in whale sharks. https://doi.org/10.1071/PC20043

Papastamatiou, Y., & Lowe, C. (n.d.). Variations in gastric acid secretion during periods offasting between two species of shark,. Comparative Biochemistry and Physiology Part A:Molecular & Integrative Physiology,, 141(2), 210-214.https://doi.org/10.1016/j.cbpb.2005.05.041.

Pethybridge, H. R., Parrish, C. C., Bruce, B. D., Young, J. W., & Nichols, P. D. (2014). Lipid,fatty acid and energy density profiles of white sharks: insights into the feeding ecologyand ecophysiology of a complex top predator. PloS one, 9(5), e97877.https://doi.org/10.1371/journal.pone.0097877

U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, 2019.Fdc.nal.usda.gov

Withers, P. (1992). Comparative animal physiology. Saunders College Publishing.

Wetherbee, B., Gruber, S., & Cortes, E. (2001). Biology: Life History. Diet, Feeding Habits,Digestion, and Consumption in Sharks, with Special Reference to Lemon Shark, NegarionBrevirostros.https://www.researchgate.net/profile/Bradley-Wetherbee/publication/261099186_Diet_feeding_habits_and_consumption_in_sharks_with_special_reference_to_the_lemon_shark_Negaprion_brevirostris/links/54984aaa0cf2519f5a1ddd9d/Diet-feeding-habits-and-consumption-i

Appendix:

(Tran, Enos, 2021)

DMR 47941.2 kJ/h (24)h/1 day = 1150588.8 kJ/day

Withers (1992)

Carbs 15.9 kJ/g - 180 g/mol

Fat 39.2 kJ/g - 256 g/mol

Protein 20.1 kJ/g - 135 g/mol

Blue whaleLockyer, C. (1991)Nishiwaki, M. (1950)

Protein - 19.715%Carbohydrates - 0 %Fat - 13.56%indigestible - 8.845%Water - 57.88%

Carbs 15.9 kJ/g - 180 g/mol

Fat 39.2 kJ/g - 256 g/mol

Protein 20.1 kJ/g - 135 g/mol

15.9 (0) = 0

39.2 (.1356) = 5.31552 kJ/g

20.1 (.19715) = 3.962715 kJ/g

= 9.278235 kJ/g

1150588.8 kJ/day / 9.278235 kJ/g = 124009.44 g/day

(Hoffmayer, Parsons, 2003)

Absorbtion 80%

124009.44 g/day / 0.8 = 155011.8 g/day

Protein, fats, carbs per day

Fats - 155011.8 g/day (.1356) = 21019.60 g/day

Protein - 155011.8 g/day (.19715) = 30560.57 g/day

Carbs - 155011.8 g/day (0) = 0 g/day

Fats 21019.60 g/day / 256 g/mol = 82.1078 mol / day

Protein 30560.57 g/day / 135 g/mol = 226.374 mol / day

Carbs 0 g/day / 180 g/mol = 0 mol /day

Average amount of food eaten according to whale

(NOAA, 2020)300,000 lbs = 136,077,711 g

136,077,711 g / 155011.8 g = 0.001139 (100) 0.1% of the whale a day

Glucose needed for brain

569.1 kJ/hr (24 h/day) = 13658.4 kJ/day (0.02) = 273.168 kJ/day / 15.9 kJ/g = 17.180 g/day

Glucose was obtained from gluconeogenesis

Surface area

86 nmole/min/cm^2 20 C (Withers)

Q10 = (R2/R1)^10/(T2-T1)

2.5 = (R1/86) ^10/(25-20)

2.5 = (86/R2)/ (25-20)^10 = 110.71 nmole/min/cm^2

110.71 nmole/min/cm^2 (1mole/ 1,000,000,000)(1440 min / day) =

0.0001594 mole/day/cm^2

226.374 mol/day / 0.0001594 mole/day/cm = 1,420,163.11 cm^2

Intestinal length

(Happyalita, 2019)

34.4 cm x 2 cm outer / inner 1 cm for 65 cm shark

Diameter percentage 1/ 34.4 (100) = 2.906 %

Length percentage 34.4/65 (100) = 52.92%

Megalodon 15 m = 1500 cm

Length 1500 cm (.5292) = 793.8 cm

Diameter 793.8cm (0.02906)= 23.067 cm

1,420,163.11 cm^2 = pi (23.067 cm)(l) = 19597.349 cm = 195.97 m

Intestinal Volume

V = (pi) 1cm ^2 (19597.349 cm ) = 61566.887 liters

Mako Shark

(FoodData, 2019)

Protein 21.43

Fat 4.11

Carbs 0

Water = 60

indigestibe = 14.11

15.9 (0) = 0

39.2 (.0411) = 1.61112 kJ/g

20.1 (.2143) = 4.30743 kJ/g

= 5.91855 kJ/g

1150588.8 kJ/day / 5.91855 kJ/g = 194403.832 g/day

Absorbtion 80%

194403.832 g/day / 0.8 = 243004.79 g/day

Protein, fats, carbs per day

Fats - 243004.79 g/day (.0411) = 9987.4968 g/day

Protein - 243004.79 g/day (.2143) = 52075.9265 g/day

Carbs - 243004.79 g/day (0) = 0 g/day

Fats - 9987.4968 g/day / 256 g/mol = 39.013659 mol / day

Protein - 52075.9265 g/day / 135 g/mol = 385.7476 mol / day

Carbs - 0 g/day / 180 g/mol = 0 mol /day

Average amount of food eaten according to mako shark weight

(Alahyene, 2020)200 kg = 200000 g

200000g / 243004.79 g/day =0.8230 (100) 82.3% of a mako shark a day

Seal

(FoodData, 2019)

Protein - 25.8

Fat - 5.88

Carbs - 0

Water = 60.2

indigestible = 7.12

15.9 (0) = 0

39.2 (.0588) = 2.30496 kJ/g

20.1 (.258) = 5.1858 kJ/g

= 7.49076 kJ/g

1150588.8 kJ/day / 5.92276kJ/g = 153601.0765 g/day

Absorbtion 80%

153601.0765 g/day / 0.8 = 192001.3457 g/day

Protein, fats, carbs per day

Fats - 192001.3457g/day (.0588) = 11289.67913 g/day

Protein - 192001.3457g/day (.258) = 49536.34719 g/day

Carbs - 192001.3457g/day (0) = 0 g/day

Fats - 11289.67913 g/day / 256 g/mol = 44.1 mol / day

Protein - 49536.34719 g/day / 135 g/mol = 366.9359 mol / day

Carbs - 0 g/day / 180 g/mol = 0 mol /day

Average amount of food eaten according to sea lion weight

(NOAA, 2020)

450 lbs = 204117g

204117 g / 192001.3457 g/day = 1.0631 (100) 100.06 % of a sea lion a day