Animal Diversity Web

Ge­o­graphic Range

Pen­nella bal­aenopterae is found in the Antarc­tic seas and the West­ern and North­ern Pa­cific Ocean. (Dal­lay and Vo­gel­bein, 1991)

• Biogeographic Regions
• antarctica
• pacific ocean

Habi­tat

The de­fin­i­tive hosts for Pen­nella bal­aenopterae are the Sei and Minke Whales (Bal­aenoptera bo­re­alis and Bal­aenoptera acu­toros­trata, re­spec­tively) of the Antarc­tic and North Pa­cific re­gions of the world. There have been some in­ter­me­di­ate hosts found for species of the Pen­nel­l­i­dae fam­ily that are im­por­tant for the life cycle of the species. Al­though the in­ter­me­di­ate host of Pen­nella bal­aenopterae is not known, this is not the case with all other cope­po­dids. (Bliss, 1982; Dal­lay and Vo­gel­bein, 1991; Uchida, et al., 1998)

• Habitat Regions
• saltwater or marine

• Aquatic Biomes
• pelagic

Phys­i­cal De­scrip­tion

Pen­nella bal­aenopterae may reach up to 30 cen­time­ters long, and thus is one of the largest species of cope­pods within its fam­ily. Adult fe­males are char­ac­ter­ized by a loss of ex­ter­nal seg­men­ta­tion and ob­scu­ra­tion of swim­ming ap­pendages. Pen­nella species are rec­og­nized by the branched out­growths on the pos­te­rior part of their trunks. The mandibles are pro­longed, form­ing a suck­ing tube for the mouth through which the species feed. Adults also have paired, seg­mented sen­sory an­ten­nae. Five pairs of tho­racic legs are found in the species, which are more mod­i­fied in fe­males than males. After at­tach­ing to the host the par­a­site un­der­goes dipha­sic growth. The first phase of this type of growth oc­curs in the cope­pod's an­te­rior body por­tion. Dur­ing the sec­ond phase of growth, the pos­te­rior por­tion, des­ig­nated pri­mar­ily for re­pro­duc­tive processes, be­gins to grow ex­tremely rapidly, and is soon larger than the an­te­rior por­tion. (Bliss, 1982; Roberts and Janovy, Jr., 2000)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes shaped differently

• Range length

  30 (high) cm

  11.81 (high) in

De­vel­op­ment

The life cycle of Pen­nel­l­i­dae species has not been fully stud­ied. How­ever, the typ­i­cal cope­po­did life cycle is com­prised of sev­eral stages, where there is a free-liv­ing stage within which the cope­pod un­der­goes sev­eral se­ries of molts until the in­fec­tive im­ma­ture stage is reached. Also char­ac­ter­is­tic of this order is the ex­is­tence of an in­ter­me­di­ate host in the life cycle, usu­ally a fish of some sort, but some­times other ver­te­brates are used. The early de­vel­op­ment of the lar­vae takes place in the egg sac while it is still at­tached to the fe­male cope­po­did, which then de­vel­ops more and is ul­ti­mately re­leased into the water pos­sess­ing a full set of cephalic ap­pendages and three pairs of tho­racic legs. The cope­pod then finds its in­ter­me­di­ate host where it re­mains until it reaches its later cope­po­did stages. After de­vel­op­ment of the at­tach­ment mouth­parts, the cope­pod finds its de­fin­i­tive host where it then per­ma­nently at­taches. En­gorged fe­males can pro­duce from 300 to 700 eggs in each of her paired egg sacs. (Bliss, 1982; Roberts and Janovy, Jr., 2000)

Re­pro­duc­tion

Both sexes dif­fer. Fe­males have dis­tinc­tive an­chor­ing processes that ex­tend from the an­te­rior end of the par­a­site. Mat­ing oc­curs after both sexes have reached full sex­ual ma­tu­rity. After cop­u­la­tion, the cope­pod male dies early on in the cy­clopo­did stage of the life cycle. The fe­male then loses all ex­ter­nal seg­men­ta­tion and grows dras­ti­cally in size. Both tem­per­a­ture and salin­ity are im­por­tant fac­tors to en­sure suc­cess­ful re­pro­duc­tion. (Bliss, 1982; Roberts and Janovy, Jr., 2000)

• Key Reproductive Features
• sexual
• fertilization
  • internal
• oviparous

• Parental Investment
• pre-fertilization
  • provisioning

Be­hav­ior

Pen­nella bal­aenopterae is a soli­tary species with no so­cial be­hav­ior with oth­ers of its species, ex­cept dur­ing mat­ing. Once it has at­tached to its host, it no longer moves around, ex­cept in the case of the male when search­ing for the fe­male to mate. The fe­male at­taches to the host after the de­vel­op­ment of two cephalic an­chor­ing ap­pendages. One of the pairs de­vel­ops from the pos­te­rior cor­ners of the cephalotho­rax and the sec­ond from the ven­tral sur­face of the cephalon. As the fe­male fur­ther de­vel­ops, the processes ex­pand and bi­fur­cate al­low­ing the fe­male to deeply ex­tend her­self per­ma­nently into the whale's blub­ber. The egg sacs are thus car­ried ex­ter­nally and the nau­plii are then re­leased into the water, thus start­ing an­other se­ries of life cy­cles. (Bliss, 1982)

• Key Behaviors
• parasite
• motile
• sedentary

Com­mu­ni­ca­tion and Per­cep­tion

Adults also have paired, seg­mented sen­sory an­ten­nae. Crus­taceans in gen­eral have var­i­ous sen­sory res­cep­tors, mainly setae over the body. Pho­tore­cep­tors are also gen­er­ally pre­sent. (Br­usca and Br­usca, 2003; Roberts and Janovy, Jr., 2000)

• Communication Channels
• tactile
• chemical

• Perception Channels
• tactile
• chemical

Food Habits

Pen­nella bal­aenopterae is an ec­topar­a­site of whales. It feeds by si­phon­ing blood from the host through its elon­gate mandibles, which are the par­a­site's pri­mary mouth­parts. (Dal­lay and Vo­gel­bein, 1991; Roberts and Janovy, Jr., 2000)

• Primary Diet
• carnivore
  • sanguivore
  • eats body fluids

• Animal Foods
• blood
• body fluids

Pre­da­tion

This free-liv­ing stage of this species is likely eaten by fish or other cope­pod preda­tors. Eggs and younger stages have a high mor­tal­ity prob­a­bly due to not reach­ing a suit­able host.

Ecosys­tem Roles

The de­fin­i­tive hosts for Pen­nella bal­aenopterae are the Sei and Minke Whales (Bal­aenoptera bo­re­alis and Bal­aenoptera acu­toros­trata, re­spec­tively) of the Antarc­tic and North Pa­cific re­gions of the world. There have been some in­ter­me­di­ate hosts found for species of the Pen­nel­l­i­dae fam­ily that are im­por­tant for the life cycle of the species. Al­though the in­ter­me­di­ate host of Pen­nella bal­aenopterae is not known, this is not the case with all other cope­po­dids. (Bliss, 1982; Dal­lay and Vo­gel­bein, 1991; Uchida, et al., 1998)

• Ecosystem Impact
• parasite

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Al­though the Pen­nel­l­i­dae species do not have a di­rect ef­fect on hu­mans, they do have an im­pact on the whal­ing in­dus­try as they af­fect the ex­te­rior, and some­time the in­te­rior, parts of the whales. In­fested whales tend to have scars and le­gions on the sur­face of their blub­ber. (Bliss, 1982; Dal­lay and Vo­gel­bein, 1991; Uchida, et al., 1998)

Con­trib­u­tors

Nagla Fe­touh (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Teresa Friedrich (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Bliss, D. 1982. The Bi­ol­ogy of crus­tacea. New York: Aca­d­e­mic Press.

Br­usca, R., G. Br­usca. 2003. In­ver­te­brates. Sun­der­land, Mass­a­chu­setts: Sin­auer As­so­ci­ates, Inc..

Cressey, R. 1982. The Bi­ol­ogy of Crus­tacea, Patho­bi­ol­ogy. New York: Aca­d­e­mic Press.

Dal­lay, M., W. Vo­gel­bein. 1991. Par­a­site Fauna of Three Species of Antarc­tic Whales with Ref­er­ence to Their Use as Po­ten­tial Stock In­di­ca­tors. Fish­ery Bul­letin, 89(3): 355-364.

Roberts, L., J. Janovy, Jr.. 2000. Foun­da­tions of Par­a­sitol­ogy. U.S.: Mc­Graw Hill.

Uchida, A., Y. Kawakami, S. Yuzu, S. Kishikawa, T. Ku­ramochi. 1998. Preva­lence of Par­a­sites and Histopathol­ogy of Par­a­siti­sa­tion in Minke Whales from the West­ern North Pa­cific Ocean and South­ern Sea of Okhotsk. Re­port of the In­ter­na­tional Whal­ing Com­mis­sion, 48: 475-479.