Formation of the gut in the first two naupliar stages of Acartia clausi and Hemidiaptomus roubaui (Copepoda, Calanoida): comparative structural and ultrastructural aspects

Abstract

In this study, the structure and ultrastructure of the digestive system are compared in the early larval stages (nauplii I and II) of two copepod calanoid species, Acartia clausi Giesbrecht, 1889 and Hemidiaptomus roubaui Richard, 1888. The nauplii I of both species have no functional digestive tract, which is represented initially only by a blind esophageal slit and yolky endodermal cells, which fill the most part of the naupliar body, whereas at the nauplius II stage the differentiated digestive tract becomes functional. The resorption cavity corresponding to the future midgut is progressively formed in the endodermal mass during the premolt phase; it is surrounded by differentiating epithelial cells. In the ecdysial phase the foregut has associated labral glands, the midgut young R-, B-, and R'-cells of epithelium, and there is a short open hindgut.

Bloom-Forming Cyanobacteria Support Copepod Reproduction and Development in the Baltic Sea

“…and E. affinis . The younger nauplial stages (NI–NII) were considered non-feeding [44] and thus not included in the analysis. Individual specimens were picked from the RNA later preserved samples, rinsed and transferred to Eppendorf tubes (5–7 ind.…”

Projected marine climate change: effects on copepod oxidative status and reproduction

“…No nauplii older than N 2 were found; thus, they were nonfeeding (Baud et al. ). Egg production rate (eggs female −1 day −1 ) was calculated using all eggs and nauplii.…”

“…where N i is the assigned stage value ( N 0 [egg] = 0; N 1 = 1; N 2 = 2) and n i is the number of copepods at that stage. No nauplii older than N 2 were found; thus, they were nonfeeding (Baud et al 2002 ). Egg production rate (eggs female −1 day −1 ) was calculated using all eggs and nauplii.…”

Acute and chronic toxicity assessments of 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) on the calanoid copepod Acartia clausi: Effects on survival, development, sex-ratio and reproduction

“…Cohorts were fed ad libitum (>300 g C L − 1 ) with Dunaliella salina (20.000 cells mL -1 ), Nannochloris sp. (10.000 cells mL -1 ), and I. galbana (100.000 cells mL -1 ) in the ratio of 1:1:1 from N2 to adult, as the first naupliar stage does not have a mouth (Baud et al, 2002). Algal cell concentration was estimated daily with a Malassez cell and adjusted from counts.…”